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BACKGROUND AND AIMS: Developing novel therapies to battle the global public health burden of heart failure remains challenging. This study investigates the underlying mechanisms and potential treatment for 4-hydroxynonenal (4-HNE) deleterious effects in heart failure. METHODS: Biochemical, functional, and histochemical measurements were applied to identify 4-HNE adducts in rat and human failing hearts. In vitro studies were performed to validate 4-HNE targets. RESULTS: 4-HNE, a reactive aldehyde by-product of mitochondrial dysfunction in heart failure, covalently inhibits Dicer, an RNase III endonuclease essential for microRNA (miRNA) biogenesis. 4-HNE inhibition of Dicer impairs miRNA processing. Mechanistically, 4-HNE binds to recombinant human Dicer through an intermolecular interaction that disrupts both activity and stability of Dicer in a concentration- and time-dependent manner. Dithiothreitol neutralization of 4-HNE or replacing 4-HNE-targeted residues in Dicer prevents 4-HNE inhibition of Dicer in vitro. Interestingly, end-stage human failing hearts from three different heart failure aetiologies display defective 4-HNE clearance, decreased Dicer activity, and miRNA biogenesis impairment. Notably, boosting 4-HNE clearance through pharmacological re-activation of mitochondrial aldehyde dehydrogenase 2 (ALDH2) using Alda-1 or its improved orally bioavailable derivative AD-9308 restores Dicer activity. ALDH2 is a major enzyme responsible for 4-HNE removal. Importantly, this response is accompanied by improved miRNA maturation and cardiac function/remodelling in a pre-clinical model of heart failure. CONCLUSIONS: 4-HNE inhibition of Dicer directly impairs miRNA biogenesis in heart failure. Strikingly, decreasing cardiac 4-HNE levels through pharmacological ALDH2 activation is sufficient to re-establish Dicer activity and miRNA biogenesis; thereby representing potential treatment for patients with heart failure.
Assuntos
Insuficiência Cardíaca , MicroRNAs , Humanos , Ratos , Animais , MicroRNAs/metabolismo , Ribonuclease III/genética , Ribonuclease III/metabolismo , Aldeídos/metabolismo , Aldeídos/farmacologia , Processamento de Proteína Pós-Traducional , Aldeído-Desidrogenase Mitocondrial/genéticaAssuntos
Distrofia Muscular de Duchenne , Envelhecimento , Aldeídos , Homeostase , Humanos , Músculo Esquelético , OxirredutasesRESUMO
ß2 -adrenoceptor agonists improve autophagy and re-establish proteostasis in cardiac cells; therefore, suggesting autophagy as a downstream effector of ß2 -adrenoceptor signaling pathway. Here, we used the pharmacological and genetic tools to determine the autophagy effect of sustained ß2 -adrenoceptor activation in rodents with neurogenic myopathy, which display impaired skeletal muscle autophagic flux. Sustained ß2 -adrenoceptor activation using Formoterol (10 µg kg-1 day-1 ), starting at the onset of neurogenic myopathy, prevents disruption of autophagic flux in skeletal muscle 14 days after sciatic nerve constriction. These changes are followed by reduction of the cytotoxic protein levels and increased skeletal muscle cross-sectional area and contractility properties. Of interest, sustained administration of Formoterol at lower concentration (1 µg kg-1 day-1 ) induces similar improvements in skeletal muscle autophagic flux and contractility properties in neurogenic myopathy, without affecting the cross-sectional area. Sustained pharmacological inhibition of autophagy using Chloroquine (50 mg kg-1 day-1 ) abolishes the beneficial effects of ß2 -adrenoceptor activation on the skeletal muscle proteostasis and contractility properties in neurogenic myopathy. Further supporting an autophagy mechanism for ß2 -adrenoceptor activation, skeletal muscle-specific deletion of ATG7 blunts the beneficial effects of ß2 -adrenoceptor on skeletal muscle proteostasis and contractility properties in neurogenic myopathy in mice. These findings suggest autophagy as a critical downstream effector of ß2 -adrenoceptor signaling pathway in skeletal muscle.
Assuntos
Agonistas de Receptores Adrenérgicos beta 2/farmacologia , Autofagia , Músculo Esquelético/patologia , Doenças Musculares/prevenção & controle , Proteostase , Receptores Adrenérgicos beta 2/metabolismo , Animais , Fumarato de Formoterol , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Contração Muscular , Músculo Esquelético/metabolismo , Doenças Musculares/etiologia , Doenças Musculares/metabolismo , Doenças Musculares/patologia , Ratos , Ratos Sprague-Dawley , Receptores Adrenérgicos beta 2/química , Transdução de SinaisRESUMO
Disruption of mitochondrial function is a common feature of inherited mitochondrial diseases (mitochondriopathies) and many other infectious and non-infectious diseases including viral, bacterial and protozoan infections, inflammatory and chronic pain, neurodegeneration, diabetes, obesity and cardiovascular diseases. Mitochondria therefore become an attractive target for developing new therapies. In this review we describe critical mechanisms involved in the maintenance of mitochondrial functionality and discuss strategies used to identify and validate mitochondrial targets in different diseases. We also highlight the most recent preclinical and clinical findings using molecules targeting mitochondrial bioenergetics, morphology, number, content and detoxification systems in common pathologies.
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Doenças Cardiovasculares/metabolismo , Mitocôndrias/metabolismo , Animais , Doenças Cardiovasculares/tratamento farmacológico , Metabolismo Energético/efeitos dos fármacos , Humanos , Mitocôndrias/efeitos dos fármacos , Terapia de Alvo Molecular , Estresse Oxidativo/efeitos dos fármacosRESUMO
Disruption of mitochondrial function is a common feature of inherited mitochondrial diseases (mitochondriopathies) and many other infectious and non-infectious diseases including viral, bacterial and protozoan infections, inflammatory and chronic pain, neurodegeneration, diabetes, obesity and cardiovascular diseases. Mitochondria therefore become an attractive target for developing new therapies. In this review we describe critical mechanisms involved in the maintenance of mitochondrial functionality and discuss strategies used to identify and validate mitochondrial targets in different diseases. We also highlight the most recent preclinical and clinical findings using molecules targeting mitochondrial bioenergetics, morphology, number, content and detoxification systems in common pathologies.
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We previously demonstrated that beta II protein kinase C (ßIIPKC) activity is elevated in failing hearts and contributes to this pathology. Here we report that ßIIPKC accumulates on the mitochondrial outer membrane and phosphorylates mitofusin 1 (Mfn1) at serine 86. Mfn1 phosphorylation results in partial loss of its GTPase activity and in a buildup of fragmented and dysfunctional mitochondria in heart failure. ßIIPKC siRNA or a ßIIPKC inhibitor mitigates mitochondrial fragmentation and cell death. We confirm that Mfn1-ßIIPKC interaction alone is critical in inhibiting mitochondrial function and cardiac myocyte viability using SAMßA, a rationally-designed peptide that selectively antagonizes Mfn1-ßIIPKC association. SAMßA treatment protects cultured neonatal and adult cardiac myocytes, but not Mfn1 knockout cells, from stress-induced death. Importantly, SAMßA treatment re-establishes mitochondrial morphology and function and improves cardiac contractility in rats with heart failure, suggesting that SAMßA may be a potential treatment for patients with heart failure.
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Insuficiência Cardíaca/tratamento farmacológico , Proteínas de Membrana/antagonistas & inibidores , Proteínas Mitocondriais/antagonistas & inibidores , Peptídeos/farmacologia , Proteína Quinase C beta/antagonistas & inibidores , Animais , GTP Fosfo-Hidrolases/metabolismo , Técnicas de Inativação de Genes , Insuficiência Cardíaca/metabolismo , Masculino , Membranas Mitocondriais/metabolismo , Contração Miocárdica , Infarto do Miocárdio/metabolismo , Infarto do Miocárdio/patologia , Miócitos Cardíacos/efeitos dos fármacos , Fosforilação , RNA Interferente Pequeno , Ratos WistarRESUMO
Increased proteolytic activity has been widely associated with skeletal muscle atrophy. However, elevated proteolysis is also critical for the maintenance of cellular homeostasis by disposing cytotoxic proteins and non-functioning organelles. We recently demonstrated that exercise activates autophagy and re-establishes proteostasis in cardiac diseases. Here, we characterized the impact of exercise on skeletal muscle autophagy and proteostasis in a model of neurogenic myopathy induced by sciatic nerve constriction in rats. Neurogenic myopathy, characterized by progressive atrophy and impaired contractility, was paralleled by accumulation of autophagy-related markers and loss of acute responsiveness to both colchicine and chloroquine. These changes were correlated with elevated levels of damaged proteins, chaperones and pro-apoptotic markers compared to control animals. Sustained autophagy inhibition using chloroquine in rats (50 mg.kg-1.day-1) or muscle-specific deletion of Atg7 in mice was sufficient to impair muscle contractility in control but not in neurogenic myopathy, suggesting that dysfunctional autophagy is critical in skeletal muscle pathophysiology. Finally, 4 weeks of aerobic exercise training (moderate treadmill running, 5x/week, 1 h/day) prior to neurogenic myopathy improved skeletal muscle autophagic flux and proteostasis. These changes were followed by spared muscle mass and better contractility properties. Taken together, our findings suggest the potential value of exercise in maintaining skeletal muscle proteostasis and slowing down the progression of neurogenic myopathy.
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Autofagia/fisiologia , Doenças Neuromusculares/fisiopatologia , Condicionamento Físico Animal/fisiologia , Proteostase/fisiologia , Animais , Antirreumáticos/farmacologia , Autofagia/genética , Cloroquina/farmacologia , Masculino , Camundongos Knockout , Camundongos Transgênicos , Contração Muscular/efeitos dos fármacos , Contração Muscular/fisiologia , Músculo Esquelético/metabolismo , Músculo Esquelético/patologia , Atrofia Muscular/metabolismo , Atrofia Muscular/fisiopatologia , Doenças Neuromusculares/genética , Doenças Neuromusculares/metabolismo , Proteólise , Proteostase/genética , Ratos Sprague-DawleyRESUMO
We previously reported that facilitating the clearance of damaged mitochondria through macroautophagy/autophagy protects against acute myocardial infarction. Here we characterize the impact of exercise, a safe strategy against cardiovascular disease, on cardiac autophagy and its contribution to mitochondrial quality control, bioenergetics and oxidative damage in a post-myocardial infarction-induced heart failure animal model. We found that failing hearts displayed reduced autophagic flux depicted by accumulation of autophagy-related markers and loss of responsiveness to chloroquine treatment at 4 and 12 wk after myocardial infarction. These changes were accompanied by accumulation of fragmented mitochondria with reduced O2 consumption, elevated H2O2 release and increased Ca2+-induced mitochondrial permeability transition pore opening. Of interest, disruption of autophagic flux was sufficient to decrease cardiac mitochondrial function in sham-treated animals and increase cardiomyocyte toxicity upon mitochondrial stress. Importantly, 8 wk of exercise training, starting 4 wk after myocardial infarction at a time when autophagy and mitochondrial oxidative capacity were already impaired, improved cardiac autophagic flux. These changes were followed by reduced mitochondrial number:size ratio, increased mitochondrial bioenergetics and better cardiac function. Moreover, exercise training increased cardiac mitochondrial number, size and oxidative capacity without affecting autophagic flux in sham-treated animals. Further supporting an autophagy mechanism for exercise-induced improvements of mitochondrial bioenergetics in heart failure, acute in vivo inhibition of autophagic flux was sufficient to mitigate the increased mitochondrial oxidative capacity triggered by exercise in failing hearts. Collectively, our findings uncover the potential contribution of exercise in restoring cardiac autophagy flux in heart failure, which is associated with better mitochondrial quality control, bioenergetics and cardiac function.
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Autofagia , Insuficiência Cardíaca/patologia , Mitocôndrias/metabolismo , Animais , Autofagia/genética , Linhagem Celular , Sobrevivência Celular , Regulação para Baixo/genética , Masculino , Camundongos , Mitocôndrias/ultraestrutura , Dinâmica Mitocondrial , Condicionamento Físico Animal , Ratos WistarRESUMO
Disruption of mitochondrial homeostasis is a hallmark of cardiac diseases. Therefore, maintenance of mitochondrial integrity through different surveillance mechanisms is critical for cardiomyocyte survival. In this review, we discuss the most recent findings on the central role of mitochondrial quality control processes including regulation of mitochondrial redox balance, aldehyde metabolism, proteostasis, dynamics, and clearance in cardiac diseases, highlighting their potential as therapeutic targets.
RESUMO
BACKGROUND/OBJECTIVES: We previously demonstrated that reducing cardiac aldehydic load by aldehyde dehydrogenase 2 (ALDH2), a mitochondrial enzyme responsible for metabolizing the major lipid peroxidation product, protects against acute ischemia/reperfusion injury and chronic heart failure. However, time-dependent changes in ALDH2 profile, aldehydic load and mitochondrial bioenergetics during progression of post-myocardial infarction (post-MI) cardiomyopathy are unknown and should be established to determine the optimal time window for drug treatment. METHODS: Here we characterized cardiac ALDH2 activity and expression, lipid peroxidation, 4-hydroxy-2-nonenal (4-HNE) adduct formation, glutathione pool and mitochondrial energy metabolism and H2O2 release during the 4 weeks after permanent left anterior descending (LAD) coronary artery occlusion in rats. RESULTS: We observed a sustained disruption of cardiac mitochondrial function during the progression of post-MI cardiomyopathy, characterized by >50% reduced mitochondrial respiratory control ratios and up to 2 fold increase in H2O2 release. Mitochondrial dysfunction was accompanied by accumulation of cardiac and circulating lipid peroxides and 4-HNE protein adducts and down-regulation of electron transport chain complexes I and V. Moreover, increased aldehydic load was associated with a 90% reduction in cardiac ALDH2 activity and increased glutathione pool. Further supporting an ALDH2 mechanism, sustained Alda-1 treatment (starting 24h after permanent LAD occlusion surgery) prevented aldehydic overload, mitochondrial dysfunction and improved ventricular function in post-MI cardiomyopathy rats. CONCLUSION: Taken together, our findings demonstrate a disrupted mitochondrial metabolism along with an insufficient cardiac ALDH2-mediated aldehyde clearance during the progression of ventricular dysfunction, suggesting a potential therapeutic value of ALDH2 activators during the progression of post-myocardial infarction cardiomyopathy.
Assuntos
Aldeído Desidrogenase/metabolismo , Benzamidas/uso terapêutico , Benzodioxóis/uso terapêutico , Cardiomiopatias/metabolismo , Progressão da Doença , Proteínas Mitocondriais/metabolismo , Infarto do Miocárdio/metabolismo , Aldeído-Desidrogenase Mitocondrial , Aldeídos/metabolismo , Animais , Benzamidas/farmacologia , Benzodioxóis/farmacologia , Cardiomiopatias/tratamento farmacológico , Masculino , Infarto do Miocárdio/tratamento farmacológico , Ratos , Ratos WistarRESUMO
AIMS: We previously demonstrated that pharmacological activation of mitochondrial aldehyde dehydrogenase 2 (ALDH2) protects the heart against acute ischaemia/reperfusion injury. Here, we determined the benefits of chronic activation of ALDH2 on the progression of heart failure (HF) using a post-myocardial infarction model. METHODS AND RESULTS: We showed that a 6-week treatment of myocardial infarction-induced HF rats with a selective ALDH2 activator (Alda-1), starting 4 weeks after myocardial infarction at a time when ventricular remodelling and cardiac dysfunction were present, improved cardiomyocyte shortening, cardiac function, left ventricular compliance and diastolic function under basal conditions, and after isoproterenol stimulation. Importantly, sustained Alda-1 treatment showed no toxicity and promoted a cardiac anti-remodelling effect by suppressing myocardial hypertrophy and fibrosis. Moreover, accumulation of 4-hydroxynonenal (4-HNE)-protein adducts and protein carbonyls seen in HF was not observed in Alda-1-treated rats, suggesting that increasing the activity of ALDH2 contributes to the reduction of aldehydic load in failing hearts. ALDH2 activation was associated with improved mitochondrial function, including elevated mitochondrial respiratory control ratios and reduced H2O2 release. Importantly, selective ALDH2 activation decreased mitochondrial Ca(2+)-induced permeability transition and cytochrome c release in failing hearts. Further supporting a mitochondrial mechanism for ALDH2, Alda-1 treatment preserved mitochondrial function upon in vitro aldehydic load. CONCLUSIONS: Selective activation of mitochondrial ALDH2 is sufficient to improve the HF outcome by reducing the toxic effects of aldehydic overload on mitochondrial bioenergetics and reactive oxygen species generation, suggesting that ALDH2 activators, such as Alda-1, have a potential therapeutic value for treating HF patients.
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Aldeído Desidrogenase/metabolismo , Insuficiência Cardíaca/enzimologia , Mitocôndrias/enzimologia , Proteínas Mitocondriais/metabolismo , Remodelação Ventricular/fisiologia , Aldeído-Desidrogenase Mitocondrial , Animais , Insuficiência Cardíaca/fisiopatologia , Masculino , Contração Miocárdica/fisiologia , Miócitos Cardíacos/enzimologia , Ratos Wistar , Função Ventricular/fisiologiaRESUMO
Reactive oxygen and nitrogen species regulate a wide array of signaling pathways that governs cardiovascular physiology. However, oxidant stress resulting from disrupted redox signaling has an adverse impact on the pathogenesis and progression of cardiovascular diseases. In this review, we address how redox signaling and oxidant stress affect the pathophysiology of cardiovascular diseases such as ischemia-reperfusion injury, hypertension and heart failure. We also summarize the benefits of exercise training in tackling the hyperactivation of cellular oxidases and mitochondrial dysfunction seen in cardiovascular diseases.
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Doenças Cardiovasculares/metabolismo , Doenças Cardiovasculares/fisiopatologia , Exercício Físico , Estresse Oxidativo , Transdução de Sinais , Antioxidantes/metabolismo , Exercício Físico/fisiologia , Humanos , Mitocôndrias/metabolismo , Oxirredução , Espécies Reativas de Oxigênio/metabolismoRESUMO
BACKGROUND: Heart failure (HF) is known to lead to skeletal muscle atrophy and dysfunction. However, intracellular mechanisms underlying HF-induced myopathy are not fully understood. We hypothesized that HF would increase oxidative stress and ubiquitin-proteasome system (UPS) activation in skeletal muscle of sympathetic hyperactivity mouse model. We also tested the hypothesis that aerobic exercise training (AET) would reestablish UPS activation in mice and human HF. METHODS/PRINCIPAL FINDINGS: Time-course evaluation of plantaris muscle cross-sectional area, lipid hydroperoxidation, protein carbonylation and chymotrypsin-like proteasome activity was performed in a mouse model of sympathetic hyperactivity-induced HF. At the 7(th) month of age, HF mice displayed skeletal muscle atrophy, increased oxidative stress and UPS overactivation. Moderate-intensity AET restored lipid hydroperoxides and carbonylated protein levels paralleled by reduced E3 ligases mRNA levels, and reestablished chymotrypsin-like proteasome activity and plantaris trophicity. In human HF (patients randomized to sedentary or moderate-intensity AET protocol), skeletal muscle chymotrypsin-like proteasome activity was also increased and AET restored it to healthy control subjects' levels. CONCLUSIONS: Collectively, our data provide evidence that AET effectively counteracts redox imbalance and UPS overactivation, preventing skeletal myopathy and exercise intolerance in sympathetic hyperactivity-induced HF in mice. Of particular interest, AET attenuates skeletal muscle proteasome activity paralleled by improved aerobic capacity in HF patients, which is not achieved by drug treatment itself. Altogether these findings strengthen the clinical relevance of AET in the treatment of HF.
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Terapia por Exercício , Proteínas Musculares/metabolismo , Atrofia Muscular , Estresse Oxidativo , Condicionamento Físico Animal , Complexo de Endopeptidases do Proteassoma/metabolismo , Ubiquitina/metabolismo , Idoso , Idoso de 80 Anos ou mais , Animais , Feminino , Insuficiência Cardíaca/complicações , Insuficiência Cardíaca/genética , Insuficiência Cardíaca/metabolismo , Insuficiência Cardíaca/fisiopatologia , Insuficiência Cardíaca/terapia , Humanos , Peroxidação de Lipídeos/genética , Masculino , Camundongos , Camundongos Knockout , Proteínas Musculares/genética , Atrofia Muscular/etiologia , Atrofia Muscular/genética , Atrofia Muscular/metabolismo , Atrofia Muscular/fisiopatologia , Atrofia Muscular/terapia , Complexo de Endopeptidases do Proteassoma/genética , Ubiquitina/genéticaRESUMO
Aerobic exercise training (AET) is an important mechanical stimulus that modulates skeletal muscle protein turnover, leading to structural rearrangement. Since the ubiquitin-proteasome system (UPS) and calpain system are major proteolytic pathways involved in protein turnover, we aimed to investigate the effects of intensity-controlled AET on the skeletal muscle UPS and calpain system and their association to training-induced structural adaptations. Long-lasting effects of AET were studied in C57BL/6J mice after 2 or 8 wk of AET. Plantaris cross-sectional area (CSA) and capillarization were assessed by myosin ATPase staining. mRNA and protein expression levels of main components of the UPS and calpain system were evaluated in plantaris by real-time PCR and Western immunoblotting, respectively. No proteolytic system activation was observed after 2 wk of AET. Eight weeks of AET resulted in improved running capacity, plantaris capillarization, and CSA. Muscle RING finger-1 mRNA expression was increased in 8-wk-trained mice. Accordingly, elevated 26S proteasome activity was observed in the 8-wk-trained group, without accumulation of ubiquitinated or carbonylated proteins. In addition, calpain abundance was increased by 8 wk of AET, whereas no difference was observed in its endogenous inhibitor calpastatin. Taken together, our findings indicate that skeletal muscle enhancements, as evidenced by increased running capacity, plantaris capillarization, and CSA, occurred in spite of the upregulated UPS and calpain system, suggesting that overactivation of skeletal muscle proteolytic systems is not restricted to atrophying states. Our data provide evidence for the contribution of the UPS and calpain system to metabolic turnover of myofibrillar proteins and skeletal muscle adaptations to AET.
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Calpaína/biossíntese , Músculo Esquelético/metabolismo , Condicionamento Físico Animal/fisiologia , Complexo de Endopeptidases do Proteassoma/biossíntese , Ubiquitina/biossíntese , Regulação para Cima/fisiologia , Animais , Teste de Esforço/métodos , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Músculo Esquelético/enzimologia , Condicionamento Físico Animal/métodosRESUMO
Exercise training is a well-known coadjuvant in heart failure treatment; however, the molecular mechanisms underlying its beneficial effects remain elusive. Despite the primary cause, heart failure is often preceded by two distinct phenomena: mitochondria dysfunction and cytosolic protein quality control disruption. The objective of the study was to determine the contribution of exercise training in regulating cardiac mitochondria metabolism and cytosolic protein quality control in a post-myocardial infarction-induced heart failure (MI-HF) animal model. Our data demonstrated that isolated cardiac mitochondria from MI-HF rats displayed decreased oxygen consumption, reduced maximum calcium uptake and elevated H2O2 release. These changes were accompanied by exacerbated cardiac oxidative stress and proteasomal insufficiency. Declined proteasomal activity contributes to cardiac protein quality control disruption in our MI-HF model. Using cultured neonatal cardiomyocytes, we showed that either antimycin A or H2O2 resulted in inactivation of proteasomal peptidase activity, accumulation of oxidized proteins and cell death, recapitulating our in vivo model. Of interest, eight weeks of exercise training improved cardiac function, peak oxygen uptake and exercise tolerance in MI-HF rats. Moreover, exercise training restored mitochondrial oxygen consumption, increased Ca²âº-induced permeability transition and reduced H2O2 release in MI-HF rats. These changes were followed by reduced oxidative stress and better cardiac protein quality control. Taken together, our findings uncover the potential contribution of mitochondrial dysfunction and cytosolic protein quality control disruption to heart failure and highlight the positive effects of exercise training in re-establishing cardiac mitochondrial physiology and protein quality control, reinforcing the importance of this intervention as a non-pharmacological tool for heart failure therapy.
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Terapia por Exercício , Insuficiência Cardíaca/terapia , Proteínas Musculares/fisiologia , Miocárdio/metabolismo , Aldeídos/metabolismo , Animais , Cálcio/metabolismo , Células Cultivadas , Insuficiência Cardíaca/metabolismo , Peróxido de Hidrogênio/metabolismo , Masculino , Mitocôndrias Cardíacas/metabolismo , Infarto do Miocárdio/metabolismo , Infarto do Miocárdio/terapia , Miocárdio/patologia , Miócitos Cardíacos/efeitos dos fármacos , Miócitos Cardíacos/metabolismo , Oligopeptídeos/farmacologia , Oxirredução , Estresse Oxidativo , Consumo de Oxigênio , Complexo de Endopeptidases do Proteassoma/metabolismo , Inibidores de Proteassoma/farmacologia , Processamento de Proteína Pós-Traducional , Ratos , Ratos Wistar , CorridaRESUMO
AIMS: The clinical benefits of angiotensin II type 1 (AT1) receptor blockers (ARB) in heart failure (HF) include cardiac anti-remodeling and improved ventricular function. However, the cellular mechanisms underlying the benefits of ARB on ventricular function need to be better clarified. In the present manuscript, we evaluated the effects of AT1 receptor blockade on the net balance of Ca(2+) handling proteins in hearts of mice lacking α(2A) and α(2C) adrenoceptors (α(2A)/α(2C)ARKO), which develop sympathetic hyperactivity (SH) induced-HF. MAIN METHODS: A cohort of male wild-type (WT) and congenic α(2A)/α(2C)ARKO mice in a C57BL6/J genetic background (5-7mo of age) was randomly assigned to receive either placebo or ARB (Losartan, 10mg/kg for 8wks). Ventricular function (VF) was assessed by echocardiography, and cardiac myocyte width and ventricular fibrosis by a computer-assisted morphometric system. Sarcoplasmic reticulum Ca(2+) ATPase (SERCA2), phospholamban (PLN), phospho-Ser(16)-PLN, phospho-Thr(17)-PLN, phosphatase 1 (PP1), Na(+)-Ca(2+) exchanger (NCX), Ca(2+)/calmodulin-dependent protein kinase II (CaMKII) and phospho-Thr(286)-CaMKII were analyzed by Western blot. KEY FINDINGS: α(2A)/α(2C)ARKO mice displayed ventricular dysfunction, cardiomyocyte hypertrophy and cardiac fibrosis paralleled by decreased SERCA2 and increased phospho-Thr(17)-PLN, CaMKII, phospho-Thr(286)-CaMKII and NCX levels. ARB induced anti-cardiac remodeling effect and improved VF in α(2A)/α(2C)ARKO associated with increased SERCA2 and phospho-Ser(16)-PLN levels, and SERCA2:NCX ratio. Additionally, ARB decreased phospho-Thr(17)-PLN levels as well as reestablished NCX, CaMKII and phospho-Thr(286)-CaMKII toward WT levels. SIGNIFICANCE: Altogether, these data provide new insights on intracellular Ca(2+) regulatory mechanisms underlying improved ventricular function by ARB therapy in HF.