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1.
Int J Mol Sci ; 22(15)2021 Jul 23.
Artigo em Inglês | MEDLINE | ID: mdl-34360639

RESUMO

LMNA-related dilated cardiomyopathy is an inherited heart disease caused by mutations in the LMNA gene encoding for lamin A/C. The disease is characterized by left ventricular enlargement and impaired systolic function associated with conduction defects and ventricular arrhythmias. We hypothesized that LMNA-mutated patients' induced Pluripotent Stem Cell-derived cardiomyocytes (iPSC-CMs) display electrophysiological abnormalities, thus constituting a suitable tool for deciphering the arrhythmogenic mechanisms of the disease, and possibly for developing novel therapeutic modalities. iPSC-CMs were generated from two related patients (father and son) carrying the same E342K mutation in the LMNA gene. Compared to control iPSC-CMs, LMNA-mutated iPSC-CMs exhibited the following electrophysiological abnormalities: (1) decreased spontaneous action potential beat rate and decreased pacemaker current (If) density; (2) prolonged action potential duration and increased L-type Ca2+ current (ICa,L) density; (3) delayed afterdepolarizations (DADs), arrhythmias and increased beat rate variability; (4) DADs, arrhythmias and cessation of spontaneous firing in response to ß-adrenergic stimulation and rapid pacing. Additionally, compared to healthy control, LMNA-mutated iPSC-CMs displayed nuclear morphological irregularities and gene expression alterations. Notably, KB-R7943, a selective inhibitor of the reverse-mode of the Na+/Ca2+ exchanger, blocked the DADs in LMNA-mutated iPSC-CMs. Our findings demonstrate cellular electrophysiological mechanisms underlying the arrhythmias in LMNA-related dilated cardiomyopathy.


Assuntos
Arritmias Cardíacas/patologia , Cálcio/metabolismo , Cardiomiopatia Dilatada/patologia , Células-Tronco Pluripotentes Induzidas/patologia , Lamina Tipo A/genética , Mutação , Miócitos Cardíacos/patologia , Potenciais de Ação , Adulto , Arritmias Cardíacas/genética , Arritmias Cardíacas/metabolismo , Cardiomiopatia Dilatada/genética , Cardiomiopatia Dilatada/metabolismo , Diferenciação Celular , Fenômenos Eletrofisiológicos , Feminino , Humanos , Células-Tronco Pluripotentes Induzidas/metabolismo , Masculino , Pessoa de Meia-Idade , Miócitos Cardíacos/metabolismo , Linhagem
2.
Int J Mol Sci ; 22(15)2021 Jul 28.
Artigo em Inglês | MEDLINE | ID: mdl-34360813

RESUMO

Proper cardiac function depends on the coordinated expression of multiple gene networks related to fuel utilization and mitochondrial ATP production, heart contraction, and ion transport. Key transcriptional regulators that regulate these gene networks have been identified. Among them, estrogen-related receptors (ERRs) have emerged as crucial modulators of cardiac function by regulating cellular metabolism and contraction machinery. Consistent with this role, lack of ERRα or ERRγ results in cardiac derangements that lead to functional maladaptation in response to increased workload. Interestingly, metabolic inflexibility associated with diabetic cardiomyopathy has been recently associated with increased mitochondrial fatty acid oxidation and expression of ERRγ, suggesting that sustained expression of this nuclear receptor could result in a cardiac pathogenic outcome. Here, we describe the generation of mice with cardiac-specific overexpression of ERRγ, which die at young ages due to heart failure. ERRγ transgenic mice show signs of dilated cardiomyopathy associated with cardiomyocyte hypertrophy, increased cell death, and fibrosis. Our results suggest that ERRγ could play a role in mediating cardiac pathogenic responses.


Assuntos
Cardiomiopatia Dilatada/metabolismo , Miocárdio/metabolismo , Miócitos Cardíacos/metabolismo , Receptores de Estrogênio/fisiologia , Animais , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Transgênicos , Miocárdio/patologia , Miócitos Cardíacos/patologia
3.
Nat Commun ; 12(1): 4583, 2021 07 28.
Artigo em Inglês | MEDLINE | ID: mdl-34321484

RESUMO

Voltage dependent anion channel 2 (VDAC2) is an outer mitochondrial membrane porin known to play a significant role in apoptosis and calcium signaling. Abnormalities in calcium homeostasis often leads to electrical and contractile dysfunction and can cause dilated cardiomyopathy and heart failure. However, the specific role of VDAC2 in intracellular calcium dynamics and cardiac function is not well understood. To elucidate the role of VDAC2 in calcium homeostasis, we generated a cardiac ventricular myocyte-specific developmental deletion of Vdac2 in mice. Our results indicate that loss of VDAC2 in the myocardium causes severe impairment in excitation-contraction coupling by altering both intracellular and mitochondrial calcium signaling. We also observed adverse cardiac remodeling which progressed to severe cardiomyopathy and death. Reintroduction of VDAC2 in 6-week-old knock-out mice partially rescued the cardiomyopathy phenotype. Activation of VDAC2 by efsevin increased cardiac contractile force in a mouse model of pressure-overload induced heart failure. In conclusion, our findings demonstrate that VDAC2 plays a crucial role in cardiac function by influencing cellular calcium signaling. Through this unique role in cellular calcium dynamics and excitation-contraction coupling VDAC2 emerges as a plausible therapeutic target for heart failure.


Assuntos
Cálcio/metabolismo , Cardiomiopatia Dilatada/metabolismo , Homeostase , Canal de Ânion 2 Dependente de Voltagem/genética , Canal de Ânion 2 Dependente de Voltagem/metabolismo , Animais , Apoptose , Sinalização do Cálcio , Cardiomiopatia Dilatada/mortalidade , Insuficiência Cardíaca/metabolismo , Camundongos , Camundongos Knockout , Mitocôndrias/metabolismo , Membranas Mitocondriais/metabolismo , Contração Miocárdica , Miócitos Cardíacos/metabolismo , Transcriptoma
4.
Int J Mol Sci ; 22(9)2021 May 10.
Artigo em Inglês | MEDLINE | ID: mdl-34068508

RESUMO

Duchenne muscular dystrophy (DMD) is a devastating condition shortening the lifespan of young men. DMD patients suffer from age-related dilated cardiomyopathy (DCM) that leads to heart failure. Several molecular mechanisms leading to cardiomyocyte death in DMD have been described. However, the pathological progression of DMD-associated DCM remains unclear. In skeletal muscle, a dramatic decrease in stem cells, so-called satellite cells, has been shown in DMD patients. Whether similar dysfunction occurs with cardiac muscle cardiovascular progenitor cells (CVPCs) in DMD remains to be explored. We hypothesized that the number of CVPCs decreases in the dystrophin-deficient heart with age and disease state, contributing to DCM progression. We used the dystrophin-deficient mouse model (mdx) to investigate age-dependent CVPC properties. Using quantitative PCR, flow cytometry, speckle tracking echocardiography, and immunofluorescence, we revealed that young mdx mice exhibit elevated CVPCs. We observed a rapid age-related CVPC depletion, coinciding with the progressive onset of cardiac dysfunction. Moreover, mdx CVPCs displayed increased DNA damage, suggesting impaired cardiac muscle homeostasis. Overall, our results identify the early recruitment of CVPCs in dystrophic hearts and their fast depletion with ageing. This latter depletion may participate in the fibrosis development and the acceleration onset of the cardiomyopathy.


Assuntos
Cardiomiopatia Dilatada/genética , Distrofina/genética , Distrofia Muscular de Duchenne/genética , Miocárdio/metabolismo , Proteínas Proto-Oncogênicas c-kit/genética , Envelhecimento/genética , Envelhecimento/patologia , Animais , Cardiomiopatia Dilatada/metabolismo , Cardiomiopatia Dilatada/patologia , Sistema Cardiovascular/metabolismo , Sistema Cardiovascular/patologia , Dano ao DNA/genética , Modelos Animais de Doenças , Distrofina/deficiência , Regulação da Expressão Gênica/genética , Humanos , Camundongos , Camundongos Endogâmicos mdx/genética , Distrofia Muscular de Duchenne/metabolismo , Distrofia Muscular de Duchenne/patologia , Miocárdio/patologia , Miócitos Cardíacos/metabolismo , Miócitos Cardíacos/patologia , Células-Tronco/metabolismo , Células-Tronco/patologia
5.
Am J Physiol Heart Circ Physiol ; 320(6): H2339-H2350, 2021 06 01.
Artigo em Inglês | MEDLINE | ID: mdl-33989081

RESUMO

Mutations to the sarcomere-localized cochaperone protein Bcl2-associated athanogene 3 (BAG3) are associated with dilated cardiomyopathy (DCM) and display greater penetrance in male patients. Decreased protein expression of BAG3 is also associated with nongenetic heart failure; however, the factors regulating cardiac BAG3 expression are unknown. Using left ventricular (LV) tissue from nonfailing and DCM human samples, we found that whole LV BAG3 expression was not significantly impacted by DCM or sex; however, myofilament localized BAG3 was significantly decreased in males with DCM. Females with DCM displayed no changes in BAG3 compared with nonfailing. This sex difference appears to be estrogen independent, as estrogen treatment in ovariectomized female rats had no impact on BAG3 expression. BAG3 gene expression in noncardiac cells is primarily regulated by the heat shock transcription factor-1 (HSF-1). We show whole LV HSF-1 expression and nuclear localized/active HSF-1 each displayed a striking positive correlation with whole LV BAG3 expression. We further found that HSF-1 localizes to the sarcomere Z-disc in cardiomyocytes and that this myofilament-associated HSF-1 pool decreases in heart failure. The decrease of HSF-1 was more pronounced in male patients and tightly correlated with myofilament BAG3 expression. Together our findings indicate that cardiac BAG3 expression and myofilament localization are differentially impacted by sex and disease and are linked to HSF-1.NEW & NOTEWORTHY Myofilament BAG3 expression decreases in male patients with nonischemic DCM but is preserved in female patients with DCM. BAG3 expression in the human heart is tightly linked to HSF-1 expression and nuclear translocation. HSF-1 localizes to the sarcomere Z-disc in the human heart. HSF-1 expression in the myofilament fraction decreases in male patients with DCM and positively correlates with myofilament BAG3.


Assuntos
Proteínas Adaptadoras de Transdução de Sinal/metabolismo , Proteínas Reguladoras de Apoptose/metabolismo , Cardiomiopatia Dilatada/metabolismo , Ventrículos do Coração/metabolismo , Fatores de Transcrição de Choque Térmico/metabolismo , Miocárdio/metabolismo , Miócitos Cardíacos/metabolismo , Sarcômeros/metabolismo , Adulto , Idoso , Animais , Feminino , Expressão Gênica , Humanos , Masculino , Microscopia de Fluorescência , Pessoa de Meia-Idade , Miocárdio/patologia , Miócitos Cardíacos/patologia , Miofibrilas/metabolismo , Ovariectomia , Ratos , Sarcômeros/patologia , Fatores Sexuais
6.
J Mol Biol ; 433(13): 167010, 2021 06 25.
Artigo em Inglês | MEDLINE | ID: mdl-33901537

RESUMO

Cardiac troponin (cTn) is made up of three subunits, cTnC, cTnI, and cTnT. The regulatory N-terminal domain of cTnC (cNTnC) controls cardiac muscle contraction in a calcium-dependent manner. We show that calcium-saturated cNTnC can adopt two different orientations, with the "active" orientation consistent with the 2020 cryo-EM structure of the activated cardiac thin filament by Yamada et al. Using solution NMR 15N R2 relaxation analysis, we demonstrate that the two domains of cTnC tumble independently (average R2 10 s-1), being connected by a flexible linker. However, upon addition of cTnI1-77, the complex tumbles as a rigid unit (R2 30 s-1). cTnI phosphomimetic mutants S22D/S23D, S41D/S43D and dilated cardiomyopathy- (DCM-)associated mutations cTnI K35Q, cTnC D75Y, and cTnC G159D destabilize the active orientation of cNTnC, with intermediate 15N R2 rates (R2 17-23 s-1). The active orientation of cNTnC is stabilized by the flexible tails of cTnI, cTnI1-37 and cTnI135-209. Surprisingly, when cTnC is incorporated into complexes lacking these tails (cTnC-cTnI38-134, cTnC-cTnT223-288, or cTnC-cTnI38-134-cTnT223-288), the cNTnC domain is still immobilized, revealing a new interaction between cNTnC and the IT-arm that stabilizes a "dormant" orientation. We propose that the calcium sensitivity of the cardiac troponin complex is regulated by an equilibrium between active and dormant orientations, which can be shifted through post-translational modifications or DCM-associated mutations.


Assuntos
Cardiomiopatia Dilatada/genética , Mutação , Miocárdio/metabolismo , Troponina C/genética , Cálcio/metabolismo , Cardiomiopatia Dilatada/metabolismo , Humanos , Espectroscopia de Ressonância Magnética , Modelos Moleculares , Complexos Multiproteicos/química , Complexos Multiproteicos/metabolismo , Fosforilação , Ligação Proteica , Domínios Proteicos , Tropomiosina/química , Tropomiosina/metabolismo , Troponina C/química , Troponina C/metabolismo , Troponina I/química , Troponina I/metabolismo , Troponina T/química , Troponina T/metabolismo
7.
FASEB J ; 35(4): e21488, 2021 04.
Artigo em Inglês | MEDLINE | ID: mdl-33734499

RESUMO

Cardiac ankyrin repeat protein (CARP) is a cardiac-specific stress-response protein which exerts diverse effects to modulate cardiac remodeling in response to pathological stimuli. We examined the role of CARP in postnatal cardiac development and function under basal conditions in mice. Transgenic mice that selectively overexpressed CARP in heart (CARP Tg) exhibited dilated cardiac chambers, impaired heart function, and cardiac fibrosis as assessed by echocardiography and histological staining. Furthermore, the mice had a shorter lifespan and reduced survival rate in response to ischemic acute myocardial infarction. Immunofluorescence demonstrated the overexpressed CARP protein was predominantly accumulated in the nuclei of cardiomyocytes. Microarray analysis revealed that the nuclear localization of CARP was associated with the suppression of calcium-handling proteins. In vitro experiments revealed that CARP overexpression resulted in decreased cell contraction and calcium transient. In post-mortem cardiac specimens from patients with dilated cardiomyopathy and end-stage heart failure, CARP was significantly increased. Taken together, our data identified CARP as a crucial contributor in dilated cardiomyopathy and heart failure which was associated with its regulation of calcium-handling proteins.


Assuntos
Cardiomiopatia Dilatada/metabolismo , Insuficiência Cardíaca/metabolismo , Infarto do Miocárdio/etiologia , Miocárdio/metabolismo , Animais , Insuficiência Cardíaca/etiologia , Humanos , Camundongos , Proteínas Musculares/metabolismo , Infarto do Miocárdio/metabolismo , Miócitos Cardíacos/metabolismo , Proteínas Nucleares/metabolismo , Proteínas Repressoras/metabolismo
8.
Int Heart J ; 62(2): 359-366, 2021 Mar 30.
Artigo em Inglês | MEDLINE | ID: mdl-33678800

RESUMO

Dilated cardiomyopathy (DCM) is a common cause of heart failure. TTN, which encodes titin protein, is a representative causative gene of DCM, and is presented mainly as a truncation variant. However, TTN truncation variants are also found in healthy individuals, and it is therefore important to evaluate the pathogenicity of each variant. In this study, we analyzed 67 cardiomyopathy-associated genes in a male Japanese patient who was hospitalized for recurrent severe heart failure and identified a novel truncation variant, TTN Ser17456Arg fs*14. This TTN truncation variant was located in the A-band region. Moreover, the patient's mother with heart failure harbored the same variant, whereas the father and brother without heart failure did not harbor the variant. To examine the functional changes associated with the truncation variant, H9c2 cells were subjected to genome editing to generate cells with a homologous truncation variant. The cells were differentiated using all-trans-retinoic acid, and the mRNA expression of skeletal actin and cardiac actin were found to be increased and decreased, respectively, consistent with known changes in patients with DCM or heart failure. In contrast, another cell with the titin truncation variant used as a control showed no changes in heart failure-related genes. In summary, we found a novel TTN truncation variant in familial DCM patients and confirmed its functional changes using a relatively simple cell model. The novel truncation variant was identified as a pathogenic and disease-causing mutation.


Assuntos
Cardiomiopatia Dilatada/genética , Conectina/genética , DNA/genética , Mutação , Miócitos Cardíacos/metabolismo , Função Ventricular Esquerda/fisiologia , Biópsia , Cardiomiopatia Dilatada/metabolismo , Cardiomiopatia Dilatada/patologia , Conectina/metabolismo , DNA/metabolismo , Análise Mutacional de DNA , Feminino , Humanos , Japão , Masculino , Pessoa de Meia-Idade , Miócitos Cardíacos/patologia , Linhagem
9.
Int J Mol Sci ; 22(4)2021 Feb 18.
Artigo em Inglês | MEDLINE | ID: mdl-33670449

RESUMO

With more than 25 million people affected, heart failure (HF) is a global threat. As energy production pathways are known to play a pivotal role in HF, we sought here to identify key metabolic changes in ischemic- and non-ischemic HF by using a multi-OMICS approach. Serum metabolites and mRNAseq and epigenetic DNA methylation profiles were analyzed from blood and left ventricular heart biopsy specimens of the same individuals. In total we collected serum from n = 82 patients with Dilated Cardiomyopathy (DCM) and n = 51 controls in the screening stage. We identified several metabolites involved in glycolysis and citric acid cycle to be elevated up to 5.7-fold in DCM (p = 1.7 × 10-6). Interestingly, cardiac mRNA and epigenetic changes of genes encoding rate-limiting enzymes of these pathways could also be found and validated in our second stage of metabolite assessment in n = 52 DCM, n = 39 ischemic HF and n = 57 controls. In conclusion, we identified a new set of metabolomic biomarkers for HF. We were able to identify underlying biological cascades that potentially represent suitable intervention targets.


Assuntos
Biomarcadores/metabolismo , Cardiomiopatia Dilatada/genética , Epigenômica/métodos , Perfilação da Expressão Gênica/métodos , Insuficiência Cardíaca/genética , Metabolômica/métodos , Adulto , Idoso , Biomarcadores/sangue , Cardiomiopatia Dilatada/diagnóstico , Cardiomiopatia Dilatada/metabolismo , Estudos de Coortes , Epigênese Genética , Feminino , Glicólise/genética , Insuficiência Cardíaca/diagnóstico , Insuficiência Cardíaca/metabolismo , Humanos , Masculino , Pessoa de Meia-Idade , Análise de Componente Principal
10.
Cardiol Young ; 31(3): 485-487, 2021 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-33118485

RESUMO

A four- and a half-month-old girl with severe dilated cardiomyopathy due to neonatal enterovirus myocarditis, treated with diuretics and milrinone for the past 4 months, was infected with SARS-CoV-2. The disease course was characterised by high fever and gastrointestinal symptoms. Cardiac function, as measured by echocardiography, remained stable. The treatment focused on maintaining a normal heart rate and a stable fluid balance. In children with severe underlying cardiac disease, even a mild SARS-CoV-2 infection can require close monitoring and compound treatment.


Assuntos
COVID-19/fisiopatologia , Cardiomiopatia Dilatada/fisiopatologia , Diarreia/fisiopatologia , Febre/fisiopatologia , Taquicardia/fisiopatologia , Taquipneia/fisiopatologia , Disfunção Ventricular Esquerda/fisiopatologia , Vômito/fisiopatologia , COVID-19/complicações , Cardiomiopatia Dilatada/tratamento farmacológico , Cardiomiopatia Dilatada/etiologia , Cardiomiopatia Dilatada/metabolismo , Cardiotônicos/uso terapêutico , Diuréticos/uso terapêutico , Ecocardiografia , Infecções por Enterovirus/complicações , Feminino , Frequência Cardíaca , Transplante de Coração , Humanos , Lactente , Milrinona/uso terapêutico , Miocardite/complicações , Peptídeo Natriurético Encefálico/metabolismo , Fragmentos de Peptídeos/metabolismo , SARS-CoV-2 , Índice de Gravidade de Doença , Troponina T/metabolismo , Disfunção Ventricular Esquerda/tratamento farmacológico , Disfunção Ventricular Esquerda/etiologia , Disfunção Ventricular Esquerda/metabolismo , Listas de Espera , Equilíbrio Hidroeletrolítico
11.
Aging (Albany NY) ; 12(23): 24117-24133, 2020 12 02.
Artigo em Inglês | MEDLINE | ID: mdl-33303703

RESUMO

Dilated cardiomyopathy (DCM) belongs to the myocardial diseases associated with a severe impairment of cardiac function, but the question of how sex and age affect this pathology has not been fully explored. Impaired energy homeostasis, mitochondrial dysfunction, and systemic inflammation are well-described phenomena associated with aging. In this study, we investigated if DCM affects these phenomena in a sex- and age-related manner. We analyzed the expression of mitochondrial and antioxidant proteins and the inflammatory state in DCM heart tissue from younger and older women and men. A significant downregulation of Sirt1 expression was detected in older DCM patients. Sex-related differences were observed in the phosphorylation of AMPK that only appeared in older males with DCM, possibly due to an alternative Sirt1 regulation mechanism. Furthermore, reduced expression of several mitochondrial proteins (TOM40, TIM23, Sirt3, and SOD2) and genes (cox1, nd4) was only detected in old DCM patients, suggesting that age has a greater effect than DCM on these alterations. Finally, an increased expression of inflammatory markers in older, failing hearts, with a stronger pro-inflammatory response in men, was observed. Together, these findings indicate that age- and sex-related increased inflammation and disturbance of mitochondrial homeostasis occurs in male individuals with DCM.


Assuntos
Cardiomiopatia Dilatada/metabolismo , Metabolismo Energético , Mediadores da Inflamação/metabolismo , Inflamação/metabolismo , Mitocôndrias Cardíacas/metabolismo , Biogênese de Organelas , Proteínas Quinases Ativadas por AMP/metabolismo , Adolescente , Adulto , Fatores Etários , Idoso , Antioxidantes/metabolismo , Cardiomiopatia Dilatada/diagnóstico , Estudos de Casos e Controles , Feminino , Humanos , Inflamação/diagnóstico , Masculino , Pessoa de Meia-Idade , Mitocôndrias Cardíacas/patologia , Proteínas Mitocondriais/metabolismo , Fosforilação , Fatores Sexuais , Sirtuína 1/metabolismo , Sirtuína 3/metabolismo , Adulto Jovem
12.
BMC Med Genomics ; 13(1): 167, 2020 11 07.
Artigo em Inglês | MEDLINE | ID: mdl-33160353

RESUMO

BACKGROUND: Heart failure is a leading cause of human morbidity and mortality. Circular RNAs (circRNAs) are a newly discovered class of RNA that have been found to have important physiological and pathological roles. In the current study, we de novo analyzed existing whole transcriptome data from 5 normal and 5 dilated cardiomyopathy (DCM) human heart samples and compared the results with circRNAs that have been previously reported in human, mouse and rat hearts. RESULTS: Our analysis identifies a list of cardiac circRNAs that are reliably detected in multiple studies. We have also defined the top 30 most abundant circRNAs in healthy human hearts which include some with previously unrecognized cardiac roles such as circHIPK3_11 and circTULP4_1. We further found that many circRNAs are dysregulated in DCM, particularly transcripts originating from DCM-related gene loci, such as TTN and RYR2. In addition, we predict the potential of cardiac circRNAs to sponge miRNAs that have reported roles in heart disease. We found that circALMS1_6 has the highest potential to bind miR-133, a microRNA that can regulate cardiac remodeling. Interestingly, we detected a novel class of circRNAs, referred to as read-though (rt)-circRNAs which are produced from exons of two different neighboring genes. Specifically, rt-circRNAs from SCAF8 and TIAM2 were observed to be dysregulated in DCM and these rt-circRNAs have the potential to sponge multiple heart disease-related miRNAs. CONCLUSIONS: In summary, this study provides a valuable resource for exploring the function of circRNAs in human heart disease and establishes a functional paradigm for identifying novel circRNAs in other tissues.


Assuntos
Cardiomiopatia Dilatada/genética , Miocárdio/química , RNA Circular/genética , Transcriptoma , Animais , Sequência de Bases , Miosinas Cardíacas/genética , Cardiomiopatia Dilatada/metabolismo , Bases de Dados Genéticas , Ventrículos do Coração/química , Humanos , Camundongos , MicroRNAs/genética , MicroRNAs/metabolismo , Cadeias Pesadas de Miosina/genética , RNA Circular/isolamento & purificação , RNA Circular/metabolismo , RNA Mensageiro/genética , RNA Mensageiro/metabolismo , RNA-Seq , Ratos , Alinhamento de Sequência , Homologia de Sequência do Ácido Nucleico , Especificidade da Espécie
13.
PLoS Genet ; 16(11): e1009088, 2020 11.
Artigo em Inglês | MEDLINE | ID: mdl-33137814

RESUMO

Mutations in the molecular co-chaperone Bcl2-associated athanogene 3 (BAG3) are found to cause dilated cardiomyopathy (DCM), resulting in systolic dysfunction and heart failure, as well as myofibrillar myopathy (MFM), which is characterized by protein aggregation and myofibrillar disintegration in skeletal muscle cells. Here, we generated a CRISPR/Cas9-induced Bag3 knockout zebrafish line and found the complete preservation of heart and skeletal muscle structure and function during embryonic development, in contrast to morpholino-mediated knockdown of Bag3. Intriguingly, genetic compensation, a process of transcriptional adaptation which acts independent of protein feedback loops, was found to prevent heart and skeletal muscle damage in our Bag3 knockout model. Proteomic profiling and quantitative real-time PCR analyses identified Bag2, another member of the Bag protein family, significantly upregulated on a transcript and protein level in bag3-/- mutants. This implied that the decay of bag3 mutant mRNA in homozygous bag3-/- embryos caused the transcriptional upregulation of bag2 expression. We further demonstrated that morpholino-mediated knockdown of Bag2 in bag3-/- embryos evoked severe functional and structural heart and skeletal muscle defects, which are similar to Bag3 morphants. However, Bag2 knockdown in bag3+/+ or bag3+/- embryos did not result in (cardio-)myopathy. Finally, we found that inhibition of the nonsense-mediated mRNA decay (NMD) machinery by knockdown of upf1, an essential NMD factor, caused severe heart and skeletal muscle defects in bag3-/- mutants due to the blockade of transcriptional adaptation of bag2 expression. Our findings provide evidence that genetic compensation might vitally influence the penetrance of disease-causing bag3 mutations in vivo.


Assuntos
Proteínas Adaptadoras de Transdução de Sinal/deficiência , Proteínas Adaptadoras de Transdução de Sinal/genética , Proteínas Reguladoras de Apoptose/deficiência , Proteínas Reguladoras de Apoptose/genética , Cardiomiopatias/genética , Insuficiência Cardíaca/genética , Insuficiência Cardíaca/metabolismo , Proteínas de Peixe-Zebra/deficiência , Proteínas de Peixe-Zebra/genética , Proteínas Adaptadoras de Transdução de Sinal/metabolismo , Animais , Apoptose/genética , Proteínas Reguladoras de Apoptose/metabolismo , Cardiomiopatias/metabolismo , Cardiomiopatias/patologia , Cardiomiopatia Dilatada/genética , Cardiomiopatia Dilatada/metabolismo , Cardiomiopatia Dilatada/patologia , Modelos Animais de Doenças , Insuficiência Cardíaca/patologia , Chaperonas Moleculares/genética , Chaperonas Moleculares/metabolismo , Fibras Musculares Esqueléticas/metabolismo , Doenças Musculares/genética , Doenças Musculares/metabolismo , Doenças Musculares/patologia , Mutação , Miocárdio/metabolismo , Miopatias Congênitas Estruturais/metabolismo , Fenótipo , Proteômica , Peixe-Zebra , Proteínas de Peixe-Zebra/metabolismo
14.
Nucleus ; 11(1): 299-314, 2020 12.
Artigo em Inglês | MEDLINE | ID: mdl-33030403

RESUMO

Decades of studies have established that nuclear lamin polymers form the nuclear lamina, a protein meshwork that supports the nuclear envelope structure and tethers heterochromatin to the nuclear periphery. Much less is known about unpolymerized nuclear lamins in the nuclear interior, some of which are now known to undergo specific phosphorylation. A recent finding that phosphorylated lamins bind gene enhancer regions offers a new hypothesis that lamin phosphorylation may influence transcriptional regulation in the nuclear interior. In this review, we discuss the regulation, localization, and functions of phosphorylated lamins. We summarize kinases that phosphorylate lamins in a variety of biological contexts. Our discussion extends to laminopathies, a spectrum of degenerative disorders caused by lamin gene mutations, such as cardiomyopathies and progeria. We compare the prevailing hypothesis for laminopathy pathogenesis based on lamins' function at the nuclear lamina with an emerging hypothesis based on phosphorylated lamins' function in the nuclear interior.


Assuntos
Cardiomiopatia Dilatada/metabolismo , Laminas/metabolismo , Lâmina Nuclear/metabolismo , Progéria/metabolismo , Animais , Cardiomiopatia Dilatada/genética , Cardiomiopatia Dilatada/patologia , Humanos , Laminas/genética , Lâmina Nuclear/genética , Lâmina Nuclear/patologia , Fosforilação , Progéria/genética , Progéria/patologia
15.
J Biol Chem ; 295(50): 17128-17137, 2020 12 11.
Artigo em Inglês | MEDLINE | ID: mdl-33020181

RESUMO

Dilated cardiomyopathy (DCM) is associated with mutations in cardiomyocyte sarcomeric proteins, including α-tropomyosin. In conjunction with troponin, tropomyosin shifts to regulate actomyosin interactions. Tropomyosin molecules overlap via tropomyosin-tropomyosin head-to-tail associations, forming a continuous strand along the thin filament. These associations are critical for propagation of tropomyosin's reconfiguration along the thin filament and key for the cooperative switching between heart muscle contraction and relaxation. Here, we tested perturbations in tropomyosin structure, biochemistry, and function caused by the DCM-linked mutation, M8R, which is located at the overlap junction. Localized and nonlocalized structural effects of the mutation were found in tropomyosin that ultimately perturb its thin filament regulatory function. Comparison of mutant and WT α-tropomyosin was carried out using in vitro motility assays, CD, actin co-sedimentation, and molecular dynamics simulations. Regulated thin filament velocity measurements showed that the presence of M8R tropomyosin decreased calcium sensitivity and thin filament cooperativity. The co-sedimentation of actin and tropomyosin showed weakening of actin-mutant tropomyosin binding. The binding of troponin T's N terminus to the actin-mutant tropomyosin complex was also weakened. CD and molecular dynamics indicate that the M8R mutation disrupts the four-helix bundle at the head-to-tail junction, leading to weaker tropomyosin-tropomyosin binding and weaker tropomyosin-actin binding. Molecular dynamics revealed that altered end-to-end bond formation has effects extending toward the central region of the tropomyosin molecule, which alter the azimuthal position of tropomyosin, likely disrupting the mutant thin filament response to calcium. These results demonstrate that mutation-induced alterations in tropomyosin-thin filament interactions underlie the altered regulatory phenotype and ultimately the pathogenesis of DCM.


Assuntos
Citoesqueleto de Actina/química , Actinas/química , Cardiomiopatia Dilatada/genética , Mutação de Sentido Incorreto , Tropomiosina/química , Tropomiosina/genética , Citoesqueleto de Actina/genética , Citoesqueleto de Actina/metabolismo , Actinas/genética , Actinas/metabolismo , Substituição de Aminoácidos , Cardiomiopatia Dilatada/metabolismo , Dicroísmo Circular , Humanos , Simulação de Dinâmica Molecular , Tropomiosina/metabolismo
16.
Sci Rep ; 10(1): 16478, 2020 10 05.
Artigo em Inglês | MEDLINE | ID: mdl-33020536

RESUMO

Phospholamban (PLN) is an important regulator for sarcoendoplasmic reticulum (SR) calcium transport ATPase (SERCA), which uptakes Ca2+ to SR during the diastolic phase of cardiomyocytes to maintain intracellular calcium homeostasis. Mutations on PLN result in intracellular calcium disorder, myocardial contraction defect, and eventually heart failure and/or malignant ventricular arrhythmia. Since 2003, several kinds of PLN mutations have been identified in familial dilated cardiomyopathy (DCM) patients, illustrating a few clinical characteristics that differs from classical DCM patients. Herein, we report a large PLN-R14del family with typical clinical characteristics reported including relatively late-onset clinical symptoms, low-voltage in ECG, as well as frequent ventricular arrythmias. Moreover, members underwent cardiac magnetic resonance (CMR) examination showed a strikingly similar pattern of late gadolinium enhancement (LGE)-Sub-epicardial involvement in the left ventricular (LV) lateral wall with or without linear mid-wall enhancement in the interventricular septum. The former one can also present in younger PLN-R14del carriers despite completely normal LV structure and function. Meanwhile, T1 mapping also found significantly increased extracellular volume (ECV) in PLN-R14del carriers. These findings highlight the special role of CMR to phenotyping PLN-induced cardiomyopathy patients and distinguish them from other types of cardiomyopathy.


Assuntos
Proteínas de Ligação ao Cálcio/genética , Cardiomiopatia Dilatada/genética , Cardiomiopatia Dilatada/patologia , Ventrículos do Coração/patologia , Miócitos Cardíacos/patologia , Adulto , Arritmias Cardíacas/genética , Arritmias Cardíacas/metabolismo , Arritmias Cardíacas/patologia , Cardiomiopatia Dilatada/metabolismo , Meios de Contraste/metabolismo , Família , Feminino , Gadolínio/metabolismo , Ventrículos do Coração/metabolismo , Humanos , Espectroscopia de Ressonância Magnética/métodos , Pessoa de Meia-Idade , Fenótipo
17.
Nat Metab ; 2(11): 1248-1264, 2020 11.
Artigo em Inglês | MEDLINE | ID: mdl-33106689

RESUMO

In addition to fatty acids, glucose and lactate are important myocardial substrates under physiologic and stress conditions. They are metabolized to pyruvate, which enters mitochondria via the mitochondrial pyruvate carrier (MPC) for citric acid cycle metabolism. In the present study, we show that MPC-mediated mitochondrial pyruvate utilization is essential for the partitioning of glucose-derived cytosolic metabolic intermediates, which modulate myocardial stress adaptation. Mice with cardiomyocyte-restricted deletion of subunit 1 of MPC (cMPC1-/-) developed age-dependent pathologic cardiac hypertrophy, transitioning to a dilated cardiomyopathy and premature death. Hypertrophied hearts accumulated lactate, pyruvate and glycogen, and displayed increased protein O-linked N-acetylglucosamine, which was prevented by increasing availability of non-glucose substrates in vivo by a ketogenic diet (KD) or a high-fat diet, which reversed the structural, metabolic and functional remodelling of non-stressed cMPC1-/- hearts. Although concurrent short-term KDs did not rescue cMPC1-/- hearts from rapid decompensation and early mortality after pressure overload, 3 weeks of a KD before transverse aortic constriction was sufficient to rescue this phenotype. Together, our results highlight the centrality of pyruvate metabolism to myocardial metabolism and function.


Assuntos
Adaptação Fisiológica/fisiologia , Proteínas de Transporte de Ânions/metabolismo , Proteínas de Transporte da Membrana Mitocondrial/metabolismo , Miocárdio/metabolismo , Estresse Fisiológico/fisiologia , Adaptação Fisiológica/genética , Animais , Proteínas de Transporte de Ânions/genética , Cardiomegalia/diagnóstico por imagem , Cardiomegalia/genética , Cardiomegalia/metabolismo , Cardiomiopatia Dilatada/genética , Cardiomiopatia Dilatada/metabolismo , Constrição Patológica , Citosol/metabolismo , Dieta Hiperlipídica , Dieta Cetogênica , Ecocardiografia , Técnicas In Vitro , Camundongos , Camundongos Knockout , Mitocôndrias Cardíacas/metabolismo , Proteínas de Transporte da Membrana Mitocondrial/genética , Miócitos Cardíacos/metabolismo , Ácido Pirúvico/metabolismo , Estresse Fisiológico/genética
18.
Int J Mol Sci ; 21(20)2020 Oct 10.
Artigo em Inglês | MEDLINE | ID: mdl-33050457

RESUMO

Brain-derived neurotrophic factor (BDNF) is a neuronal growth and survival factor that harbors cardioprotective qualities that may attenuate dilated cardiomyopathy. In ~30% of the population, BDNF has a common, nonsynonymous single nucleotide polymorphism rs6265 (Val66Met), which might be correlated with increased risk of cardiovascular events. We previously showed that BDNF correlates with better cardiac function in Duchenne muscular dystrophy (DMD) patients. However, the effect of the Val66Met polymorphism on cardiac function has not been determined. The goal of the current study was to determine the effects of rs6265 on BDNF biomarker suitability and DMD cardiac functions more generally. We assessed cardiovascular and skeletal muscle function in human DMD patients segregated by polymorphic allele. We also compared echocardiographic, electrophysiologic, and cardiomyocyte contractility in C57/BL-6 wild-type mice with rs6265 polymorphism and in mdx/mTR (mDMD) mouse model of DMD. In human DMD patients, plasma BDNF levels had a positive correlation with left ventricular function, opposite to that seen in rs6265 carriers. There was also a substantial decrease in skeletal muscle function in carriers compared to the Val homozygotes. Surprisingly, the opposite was true when cardiac function of DMD carriers and non-carriers were compared. On the other hand, Val66Met wild-type mice had only subtle functional differences at baseline but significantly decreased cardiomyocyte contractility. Our results indicate that the Val66Met polymorphism alters myocyte contractility, conferring worse skeletal muscle function but better cardiac function in DMD patients. Moreover, these results suggest a mechanism for the relative preservation of cardiac tissues compared to skeletal muscle in DMD patients and underscores the complexity of BDNF signaling in response to mechanical workload.


Assuntos
Fator Neurotrófico Derivado do Encéfalo/genética , Cardiomiopatia Dilatada/etiologia , Cardiomiopatia Dilatada/metabolismo , Predisposição Genética para Doença , Miócitos Cardíacos/metabolismo , Polimorfismo de Nucleotídeo Único , Animais , Cardiomiopatia Dilatada/diagnóstico , Cardiomiopatia Dilatada/fisiopatologia , Modelos Animais de Doenças , Ecocardiografia , Eletrocardiografia , Regulação da Expressão Gênica , Estudos de Associação Genética , Humanos , Camundongos , Camundongos Transgênicos , Contração Miocárdica
19.
Nat Commun ; 11(1): 4416, 2020 09 04.
Artigo em Inglês | MEDLINE | ID: mdl-32887881

RESUMO

Despite the clear association between myocardial injury, heart failure and depressed myocardial energetics, little is known about upstream signals responsible for remodeling myocardial metabolism after pathological stress. Here, we report increased mitochondrial calmodulin kinase II (CaMKII) activation and left ventricular dilation in mice one week after myocardial infarction (MI) surgery. By contrast, mice with genetic mitochondrial CaMKII inhibition are protected from left ventricular dilation and dysfunction after MI. Mice with myocardial and mitochondrial CaMKII overexpression (mtCaMKII) have severe dilated cardiomyopathy and decreased ATP that causes elevated cytoplasmic resting (diastolic) Ca2+ concentration and reduced mechanical performance. We map a metabolic pathway that rescues disease phenotypes in mtCaMKII mice, providing insights into physiological and pathological metabolic consequences of CaMKII signaling in mitochondria. Our findings suggest myocardial dilation, a disease phenotype lacking specific therapies, can be prevented by targeted replacement of mitochondrial creatine kinase or mitochondrial-targeted CaMKII inhibition.


Assuntos
Proteína Quinase Tipo 2 Dependente de Cálcio-Calmodulina/metabolismo , Cardiomiopatia Dilatada/metabolismo , Infarto do Miocárdio/fisiopatologia , Animais , Cálcio/metabolismo , Proteínas de Ligação ao Cálcio/metabolismo , Proteína Quinase Tipo 2 Dependente de Cálcio-Calmodulina/genética , Metabolismo Energético/genética , Metabolismo Energético/fisiologia , Insuficiência Cardíaca/metabolismo , Ventrículos do Coração/fisiopatologia , Camundongos , Camundongos Transgênicos , Proteínas Mitocondriais/genética , Proteínas Mitocondriais/metabolismo , Infarto do Miocárdio/cirurgia , Transdução de Sinais
20.
JCI Insight ; 5(20)2020 10 15.
Artigo em Inglês | MEDLINE | ID: mdl-32931484

RESUMO

Dilated cardiomyopathy (DCM) is often associated with sarcomere protein mutations that confer reduced myofilament tension-generating capacity. We demonstrated that cardiac twitch tension-time integrals can be targeted and tuned to prevent DCM remodeling in hearts with contractile dysfunction. We employed a transgenic murine model of DCM caused by the D230N-tropomyosin (Tm) mutation and designed a sarcomere-based intervention specifically targeting the twitch tension-time integral of D230N-Tm hearts using multiscale computational models of intramolecular and intermolecular interactions in the thin filament and cell-level contractile simulations. Our models predicted that increasing the calcium sensitivity of thin filament activation using the cardiac troponin C (cTnC) variant L48Q can sufficiently augment twitch tension-time integrals of D230N-Tm hearts. Indeed, cardiac muscle isolated from double-transgenic hearts expressing D230N-Tm and L48Q cTnC had increased calcium sensitivity of tension development and increased twitch tension-time integrals compared with preparations from hearts with D230N-Tm alone. Longitudinal echocardiographic measurements revealed that DTG hearts retained normal cardiac morphology and function, whereas D230N-Tm hearts developed progressive DCM. We present a computational and experimental framework for targeting molecular mechanisms governing the twitch tension of cardiomyopathic hearts to counteract putative mechanical drivers of adverse remodeling and open possibilities for tension-based treatments of genetic cardiomyopathies.


Assuntos
Sinalização do Cálcio/genética , Cardiomiopatia Dilatada/genética , Coração/crescimento & desenvolvimento , Troponina C/genética , Substituição de Aminoácidos/genética , Animais , Cálcio/metabolismo , Cardiomiopatia Dilatada/metabolismo , Cardiomiopatia Dilatada/patologia , Coração/fisiopatologia , Humanos , Camundongos , Camundongos Transgênicos , Mutação/genética , Contração Miocárdica/genética , Miocárdio/metabolismo , Miocárdio/patologia , Miofibrilas/genética , Miofibrilas/patologia , Sarcômeros/genética , Sarcômeros/patologia
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