RESUMEN
The UbiB protein kinase-like (PKL) family is widespread, comprising one-quarter of microbial PKLs and five human homologs, yet its biochemical activities remain obscure. COQ8A (ADCK3) is a mammalian UbiB protein associated with ubiquinone (CoQ) biosynthesis and an ataxia (ARCA2) through unclear means. We show that mice lacking COQ8A develop a slowly progressive cerebellar ataxia linked to Purkinje cell dysfunction and mild exercise intolerance, recapitulating ARCA2. Interspecies biochemical analyses show that COQ8A and yeast Coq8p specifically stabilize a CoQ biosynthesis complex through unorthodox PKL functions. Although COQ8 was predicted to be a protein kinase, we demonstrate that it lacks canonical protein kinase activity in trans. Instead, COQ8 has ATPase activity and interacts with lipid CoQ intermediates, functions that are likely conserved across all domains of life. Collectively, our results lend insight into the molecular activities of the ancient UbiB family and elucidate the biochemical underpinnings of a human disease.
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Conducta Animal , Ataxia Cerebelosa/enzimología , Cerebelo/enzimología , Proteínas Mitocondriales/deficiencia , Músculo Esquelético/enzimología , Ubiquinona/deficiencia , Animales , Células COS , Ataxia Cerebelosa/genética , Ataxia Cerebelosa/fisiopatología , Ataxia Cerebelosa/psicología , Cerebelo/fisiopatología , Cerebelo/ultraestructura , Chlorocebus aethiops , Modelos Animales de Enfermedad , Tolerancia al Ejercicio , Femenino , Predisposición Genética a la Enfermedad , Células HEK293 , Humanos , Metabolismo de los Lípidos , Masculino , Aprendizaje por Laberinto , Ratones Endogámicos C57BL , Ratones Noqueados , Proteínas Mitocondriales/química , Proteínas Mitocondriales/genética , Modelos Moleculares , Actividad Motora , Fuerza Muscular , Músculo Esquelético/fisiopatología , Fenotipo , Unión Proteica , Conformación Proteica , Proteómica/métodos , Reconocimiento en Psicología , Prueba de Desempeño de Rotación con Aceleración Constante , Saccharomyces cerevisiae/enzimología , Saccharomyces cerevisiae/genética , Proteínas de Saccharomyces cerevisiae/genética , Proteínas de Saccharomyces cerevisiae/metabolismo , Convulsiones/enzimología , Convulsiones/genética , Convulsiones/fisiopatología , Relación Estructura-Actividad , Factores de Tiempo , Transfección , Ubiquinona/química , Ubiquinona/genéticaRESUMEN
BACKGROUND: Myocardial metabolic impairment is a major feature in chronic heart failure. As the major coenzyme in fuel oxidation and oxidative phosphorylation and a substrate for enzymes signaling energy stress and oxidative stress response, nicotinamide adenine dinucleotide (NAD+) is emerging as a metabolic target in a number of diseases including heart failure. Little is known on the mechanisms regulating homeostasis of NAD+ in the failing heart. METHODS: To explore possible alterations of NAD+ homeostasis in the failing heart, we quantified the expression of NAD+ biosynthetic enzymes in the human failing heart and in the heart of a mouse model of dilated cardiomyopathy (DCM) triggered by Serum Response Factor transcription factor depletion in the heart (SRFHKO) or of cardiac hypertrophy triggered by transverse aorta constriction. We studied the impact of NAD+ precursor supplementation on cardiac function in both mouse models. RESULTS: We observed a 30% loss in levels of NAD+ in the murine failing heart of both DCM and transverse aorta constriction mice that was accompanied by a decrease in expression of the nicotinamide phosphoribosyltransferase enzyme that recycles the nicotinamide precursor, whereas the nicotinamide riboside kinase 2 (NMRK2) that phosphorylates the nicotinamide riboside precursor is increased, to a higher level in the DCM (40-fold) than in transverse aorta constriction (4-fold). This shift was also observed in human failing heart biopsies in comparison with nonfailing controls. We show that the Nmrk2 gene is an AMP-activated protein kinase and peroxisome proliferator-activated receptor α responsive gene that is activated by energy stress and NAD+ depletion in isolated rat cardiomyocytes. Nicotinamide riboside efficiently rescues NAD+ synthesis in response to FK866-mediated inhibition of nicotinamide phosphoribosyltransferase and stimulates glycolysis in cardiomyocytes. Accordingly, we show that nicotinamide riboside supplementation in food attenuates the development of heart failure in mice, more robustly in DCM, and partially after transverse aorta constriction, by stabilizing myocardial NAD+ levels in the failing heart. Nicotinamide riboside treatment also robustly increases the myocardial levels of 3 metabolites, nicotinic acid adenine dinucleotide, methylnicotinamide, and N1-methyl-4-pyridone-5-carboxamide, that can be used as validation biomarkers for the treatment. CONCLUSIONS: The data show that nicotinamide riboside, the most energy-efficient among NAD precursors, could be useful for treatment of heart failure, notably in the context of DCM, a disease with few therapeutic options.
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Cardiomiopatía Dilatada/tratamiento farmacológico , Niacinamida/análogos & derivados , Proteínas Quinasas Activadas por AMP/metabolismo , Acrilamidas/uso terapéutico , Animales , Ácido Cítrico/metabolismo , Citocinas/genética , Citocinas/metabolismo , Suplementos Dietéticos , Modelos Animales de Enfermedad , Perfilación de la Expresión Génica , Insuficiencia Cardíaca/prevención & control , Metaboloma/efectos de los fármacos , Ratones , Ratones Transgénicos , Miocitos Cardíacos/citología , Miocitos Cardíacos/efectos de los fármacos , Miocitos Cardíacos/metabolismo , NAD/metabolismo , Niacinamida/uso terapéutico , Nicotinamida Fosforribosiltransferasa/genética , Nicotinamida Fosforribosiltransferasa/metabolismo , PPAR alfa/metabolismo , Fosfotransferasas (Aceptor de Grupo Alcohol)/antagonistas & inhibidores , Fosfotransferasas (Aceptor de Grupo Alcohol)/genética , Fosfotransferasas (Aceptor de Grupo Alcohol)/metabolismo , Piperidinas/uso terapéutico , Compuestos de Piridinio , Ratas , Factor de Respuesta Sérica/deficiencia , Factor de Respuesta Sérica/genéticaRESUMEN
Statins inhibit cholesterol biosynthesis and lower serum LDL-cholesterol levels. Statins are generally well tolerated, but can be associated with potentially life-threatening myopathy of unknown mechanism. We have shown previously that statins impair PGC-1ß expression in human and rat skeletal muscle, suggesting that PGC-1ß may play a role in statin-induced myopathy. PGC-1ß is a transcriptional co-regulator controlling the expression of important genes in mitochondrial biogenesis, antioxidative capacity and energy metabolism. The principle aim of the current study was to investigate the interaction between atorvastatin and PGC-1ß in more detail. We therefore treated wild-type mice and mice with selective skeletal muscle knockout of PGC-1ß (PGC-1ß(i)skm-/- mice) with oral atorvastatin (5 mg/kg/day) for 2 weeks. At the end of treatment, we determined body parameters, muscle function, structure, and composition as well as the function of muscle mitochondria, mitochondrial biogenesis and activation of apoptotic pathways. In wild-type mice, atorvastatin selectively impaired mitochondrial function in glycolytic muscle and caused a conversion of oxidative type IIA to glycolytic type IIB myofibers. Conversely, in oxidative muscle of wild-type mice, atorvastatin enhanced mitochondrial function via activation of mitochondrial biogenesis pathways and decreased apoptosis. In PGC-1ß(i)skm-/- mice, atorvastatin induced a switch towards glycolytic fibers, caused mitochondrial dysfunction, increased mitochondrial ROS production, impaired mitochondrial proliferation and induced apoptosis in both glycolytic and oxidative skeletal muscle. Our work reveals that atorvastatin mainly affects glycolytic muscle in wild-type mice and demonstrates the importance of PGC-1ß for oxidative muscle integrity during long-term exposure to a myotoxic agent.
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Atorvastatina/toxicidad , Inhibidores de Hidroximetilglutaril-CoA Reductasas/toxicidad , Músculo Esquelético/efectos de los fármacos , Miotoxicidad/etiología , Coactivador 1-alfa del Receptor Activado por Proliferadores de Peroxisomas gamma/metabolismo , Animales , Apoptosis/efectos de los fármacos , Apoptosis/fisiología , Atorvastatina/metabolismo , Femenino , Peróxido de Hidrógeno/metabolismo , Inhibidores de Hidroximetilglutaril-CoA Reductasas/metabolismo , Masculino , Ratones Endogámicos C57BL , Ratones Noqueados , Ratones Transgénicos , Mitocondrias Musculares/efectos de los fármacos , Mitocondrias Musculares/metabolismo , Mitocondrias Musculares/patología , Músculo Esquelético/metabolismo , Músculo Esquelético/patología , Cadenas Pesadas de Miosina/metabolismo , Miotoxicidad/patología , Coactivador 1-alfa del Receptor Activado por Proliferadores de Peroxisomas gamma/genéticaRESUMEN
Dermatomyositis (DM) is an autoimmune disease associated with enhanced type I interferon (IFN) signalling in skeletal muscle, but the mechanisms underlying muscle dysfunction and inflammation perpetuation remain unknown. Transcriptomic analysis of early untreated DM muscles revealed that the main cluster of down-regulated genes was mitochondria-related. Histochemical, electron microscopy, and in situ oxygraphy analysis showed mitochondrial abnormalities, including increased reactive oxygen species (ROS) production and decreased respiration, which was correlated with low exercise capacities and a type I IFN signature. Moreover, IFN-ß induced ROS production in human myotubes was found to contribute to mitochondrial malfunctions. Importantly, the ROS scavenger N-acetyl cysteine (NAC) prevented mitochondrial dysfunctions, type I IFN-stimulated transcript levels, inflammatory cell infiltrate, and muscle weakness in an experimental autoimmune myositis mouse model. Thus, these data highlight a central role of mitochondria and ROS in DM. Mitochondrial dysfunctions, mediated by IFN-ß induced-ROS, contribute to poor exercise capacity. In addition, mitochondrial dysfunctions increase ROS production that drive type I IFN-inducible gene expression and muscle inflammation, and may thus self-sustain the disease. Given that current DM treatments only induce partial recovery and expose to serious adverse events (including muscular toxicity), protecting mitochondria from dysfunctions may open new therapeutic avenues for DM.
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Dermatomiositis/metabolismo , Inflamación/metabolismo , Interferón beta/metabolismo , Mitocondrias/metabolismo , Músculo Esquelético/metabolismo , Especies Reactivas de Oxígeno/metabolismo , Acetilcisteína/farmacología , Adulto , Anciano , Animales , Línea Celular , Citocinas/sangre , Dermatomiositis/tratamiento farmacológico , Dermatomiositis/patología , Femenino , Depuradores de Radicales Libres/farmacología , Adyuvante de Freund , Humanos , Inflamación/tratamiento farmacológico , Inflamación/patología , Masculino , Ratones Endogámicos BALB C , Persona de Mediana Edad , Mitocondrias/efectos de los fármacos , Mitocondrias/patología , Debilidad Muscular/tratamiento farmacológico , Debilidad Muscular/metabolismo , Debilidad Muscular/patología , Músculo Esquelético/efectos de los fármacos , Músculo Esquelético/patología , Enfermedad Autoinmune Experimental del Sistema Nervioso/tratamiento farmacológico , Enfermedad Autoinmune Experimental del Sistema Nervioso/metabolismo , Enfermedad Autoinmune Experimental del Sistema Nervioso/patología , TranscriptomaRESUMEN
Peripheral artery disease (PAD) is a common circulatory disorder of the lower limb arteries that reduces functional capacity and quality of life of patients. Despite relatively effective available treatments, PAD is a serious public health issue associated with significant morbidity and mortality. Ischemia-reperfusion (I/R) cycles during PAD are responsible for insufficient oxygen supply, mitochondriopathy, free radical production, and inflammation and lead to events that contribute to myocyte death and remote organ failure. However, the chronology of mitochondrial and cellular events during the ischemic period and at the moment of reperfusion in skeletal muscle fibers has been poorly reviewed. Thus, after a review of the basal myocyte state and normal mitochondrial biology, we discuss the physiopathology of ischemia and reperfusion at the mitochondrial and cellular levels. First we describe the chronology of the deleterious biochemical and mitochondrial mechanisms activated by I/R. Then we discuss skeletal muscle I/R injury in the muscle environment, mitochondrial dynamics, and inflammation. A better understanding of the chronology of the events underlying I/R will allow us to identify key factors in the development of this pathology and point to suitable new therapies. Emerging data on mitochondrial dynamics should help identify new molecular and therapeutic targets and develop protective strategies against PAD.
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Mitocondrias Musculares/metabolismo , Músculo Esquelético/irrigación sanguínea , Músculo Esquelético/metabolismo , Enfermedad Arterial Periférica/metabolismo , Daño por Reperfusión/metabolismo , Animales , Metabolismo Energético , Humanos , Mediadores de Inflamación/metabolismo , Mitocondrias Musculares/patología , Músculo Esquelético/patología , Estrés Oxidativo , Enfermedad Arterial Periférica/patología , Enfermedad Arterial Periférica/fisiopatología , Daño por Reperfusión/patología , Daño por Reperfusión/fisiopatología , Transducción de Señal , Factores de TiempoRESUMEN
Even though oxidative stress damage from excessive production of ROS is a well known phenomenon, the impact of reductive stress remains poorly understood. This study tested the hypothesis that cellular reductive stress could lead to mitochondrial malfunction, triggering a mitochondrial hormesis (mitohormesis) phenomenon able to protect mitochondria from the deleterious effects of statins. We performed several in vitro experiments on L6 myoblasts and studied the effects of N-acetylcysteine (NAC) at different exposure times. Direct NAC exposure (1mM) led to reductive stress, impairing mitochondrial function by decreasing maximal mitochondrial respiration and increasing H2O2production. After 24h of incubation, the reactive oxygen species (ROS) production was increased. The resulting mitochondrial oxidation activated mitochondrial biogenesis pathways at the mRNA level. After one week of exposure, mitochondria were well-adapted as shown by the decrease of cellular ROS, the increase of mitochondrial content, as well as of the antioxidant capacities. Atorvastatin (ATO) exposure (100µM) for 24h increased ROS levels, reduced the percentage of live cells, and increased the total percentage of apoptotic cells. NAC exposure during 3days failed to protect cells from the deleterious effects of statins. On the other hand, NAC pretreatment during one week triggered mitochondrial hormesis and reduced the deleterious effect of statins. These results contribute to a better understanding of the redox-dependant pathways linked to mitochondria, showing that reductive stress could trigger mitochondrial hormesis phenomenon.
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Hormesis , Mitocondrias/metabolismo , Mioblastos/metabolismo , Estrés Fisiológico , Acetilcisteína/farmacología , Animales , Respiración de la Célula/efectos de los fármacos , Supervivencia Celular/efectos de los fármacos , Citoprotección/efectos de los fármacos , Hormesis/efectos de los fármacos , Inhibidores de Hidroximetilglutaril-CoA Reductasas/farmacología , Mitocondrias/efectos de los fármacos , Recambio Mitocondrial/efectos de los fármacos , Mioblastos/efectos de los fármacos , Oxidación-Reducción/efectos de los fármacos , Sustancias Protectoras/farmacología , Ratas , Especies Reactivas de Oxígeno/metabolismo , Estrés Fisiológico/efectos de los fármacos , Factores de TiempoRESUMEN
INTRODUCTION: The goal of this study was to compare the effects of downhill (DH), uphill (UH), and UH-DH exercise training, at the same metabolic rate, on exercise capacity and skeletal muscle mitochondrial function. METHODS: Thirty-two Wistar rats were separated into a control and 3 trained groups. The trained groups exercised for 4 weeks, 5 times per week at the same metabolic rate, either in UH, DH, or combined UH-DH. Twenty-four hours after the last training session, the soleus, gastrocnemius, and vastus intermedius muscles were removed for assessment of mitochondrial respiration. RESULTS: Exercise training, at the same metabolic rate, improved maximal running speed without specificity for exercise modalities. Maximal fiber respiration was enhanced in soleus and vastus intermedius in the UH group only. CONCLUSIONS: Exercise training, performed at the same metabolic rate, improved exercise capacity, but only UH-trained rats enhanced mitochondrial function in both soleus and vastus intermedius skeletal muscle. Muscle Nerve 54: 925-935, 2016.
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Mitocondrias/fisiología , Músculo Esquelético/ultraestructura , Condicionamiento Físico Animal/fisiología , Animales , Complejo I de Transporte de Electrón/metabolismo , Ácido Láctico/sangre , Consumo de Oxígeno , Intercambio Gaseoso Pulmonar , Ratas , Ratas Wistar , Especies Reactivas de Oxígeno/metabolismo , Carrera/fisiología , Estadísticas no ParamétricasRESUMEN
OBJECTIVE: Lower limb ischemia-reperfusion results in skeletal muscle mitochondrial alterations, production of reactive oxygen species (ROS), and remote organ impairments that are largely involved in patient prognosis. However, whether ischemia without reperfusion increases ROS production and precedes mitochondrial alteration and whether mitochondrial dysfunction occurs early in remote organs is unknown. This study determined muscle mitochondrial function and ROS production after ischemia alone, or followed by two periods of reperfusion, and investigated heart, lung, liver, kidney, and brain mitochondrial functions after lower limb ischemia-reperfusion. METHODS: Wistar rats were randomized into four groups: sham (aortic exposure but no ischemia, n = 9), I3 (ischemia alone induced by aortic cross-clamping for 3 hours, n = 9), I3R10' and I3R2 (aortic cross-clamping, followed by reperfusion for 10 minutes [n = 8] or 2 hours [n = 9]). Blood lactate, alanine aminotransferase, aspartate aminotransferase, and creatinine were measured. Mitochondrial respiratory chain complexes I, II, III, and IV activities and mitochondrial coupling (acceptor control ratio) were analyzed using a Clark oxygen electrode in skeletal muscle, lung, heart, brain, liver, and kidney. ROS production was determined using dihydroethidium staining in muscle, heart, liver, and kidney. Inflammation was also investigated in remote organs (heart, liver, and kidney) using monocyte-macrophage-2 antibody staining. RESULTS: Lactate level increased after ischemia in all groups. In muscle, ROS increased significantly after ischemia alone (+324% ± 66%; P = .038), normalized after 10 minutes of reperfusion, and increased again at 2 hours of reperfusion (+349.2 ± 67%; P = .024). Interestingly, mitochondrial function was unaffected by ischemia alone or followed by 10 minutes of reperfusion, but maximal mitochondrial oxidative capacity (6.10 ± 0.51 vs. 4.24 ± 0.36 µmol/min/g, -30%; P < .05) and mitochondrial coupling decreased after 2 hours of reperfusion (1.93 ± 0.17 vs. 1.33 ± 0.07, -45%; P < .01), in sham and I3R2 rats, respectively. Despite increased serum aspartate aminotransferase (×13; P < .0001), alanine aminotransferase (×6; P = .0019), and creatinine (×3; P = .0004), remote organs did not show mitochondrial alteration, inflammation, or ROS production enhancement after 2 hours of reperfusion. CONCLUSIONS: Oxidative stress precedes skeletal muscle mitochondrial dysfunction during lower limb ischemia. Such a kinetic explains the efficacy of ischemic preconditioning and supports that therapy should be conducted even during ongoing ischemia, suggesting that ischemic preconditioning might be a successful approach.
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Riñón/metabolismo , Hígado/metabolismo , Pulmón/metabolismo , Mitocondrias/metabolismo , Enfermedades Mitocondriales/metabolismo , Estrés Oxidativo/fisiología , Daño por Reperfusión/metabolismo , Animales , Aorta Abdominal/cirugía , Modelos Animales de Enfermedad , Inmunohistoquímica , Precondicionamiento Isquémico , Riñón/patología , Hígado/patología , Extremidad Inferior/irrigación sanguínea , Pulmón/patología , Masculino , Mitocondrias Cardíacas/metabolismo , Mitocondrias Hepáticas/metabolismo , Enfermedades Mitocondriales/etiología , Ratas , Ratas Wistar , Especies Reactivas de Oxígeno/metabolismo , Daño por Reperfusión/patologíaRESUMEN
Mitochondria are considered as the powerhouse of eukaryotic cells. They host several central metabolic processes fueling the oxidative phosphorylation pathway (OXPHOS) that produces ATP from its precursors ADP and inorganic phosphate Pi (PPi). The respiratory chain complexes responsible for the OXPHOS pathway are formed from complementary sets of protein subunits encoded by the nuclear genome and the mitochondrial genome, respectively. The expression of the mitochondrial genome requires a specific and fully active translation machinery from which aminoacyl-tRNA synthetases (aaRSs) are key actors. Whilst the macromolecules involved in mammalian mitochondrial translation have been under investigation for many years, there has been an explosion of interest in human mitochondrial aaRSs (mt-aaRSs) since the discovery of a large (and growing) number of mutations in these genes that are linked to a variety of neurodegenerative disorders. Herein we will review the present knowledge on mt-aaRSs in terms of their biogenesis, their connection to mitochondrial respiration, i.e., the respiratory chain (RC) complexes, and to the mitochondrial translation machinery. The pathology-related mutations detected so far are described, with special attention given to their impact on mt-aaRSs biogenesis, functioning, and/or subsequent activities. The collected data to date shed light on the diverse routes that are linking primary molecular possible impact of a mutation to its phenotypic expression. It is envisioned that a variety of mechanisms, inside and outside the translation machinery, would play a role on the heterogeneous manifestations of mitochondrial disorders.
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Aminoacil-ARNt Sintetasas/metabolismo , Enfermedad , Mitocondrias/enzimología , Adenosina Trifosfato/biosíntesis , Aminoacil-ARNt Sintetasas/biosíntesis , Aminoacil-ARNt Sintetasas/química , Aminoacil-ARNt Sintetasas/genética , Animales , Enfermedad/genética , Humanos , Mitocondrias/metabolismoRESUMEN
INTRODUCTION: The effect of eccentric (ECC) versus concentric (CON) training on metabolic properties in skeletal muscle is understood poorly. We determined the responses in oxidative capacity and mitochondrial H2 O2 production after eccentric (ECC) versus concentric (CON) training performed at similar mechanical power. METHODS: Forty-eight rats performed 5- or 20-day eccentric (ECC) or concentric (CON) training programs. Mitochondrial respiration, H2 O2 production, citrate synthase activity (CS), and skeletal muscle damage were assessed in gastrocnemius (GAS), soleus (SOL) and vastus intermedius (VI) muscles. RESULTS: Maximal mitochondrial respiration improved only after 20 days of concentric (CON) training in GAS and SOL. H2 O2 production increased specifically after 20 days of eccentric ECC training in VI. Skeletal muscle damage occurred transiently in VI after 5 days of ECC training. CONCLUSIONS: Twenty days of ECC versus CON training performed at similar mechanical power output do not increase skeletal muscle oxidative capacities, but it elevates mitochondrial H2 O2 production in VI, presumably linked to transient muscle damage.
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Mitocondrias Musculares/fisiología , Músculo Esquelético/ultraestructura , Estrés Oxidativo/fisiología , Condicionamiento Físico Animal/fisiología , Adenosina Difosfato/metabolismo , Animales , Índice de Masa Corporal , Citrato (si)-Sintasa/metabolismo , Creatina Quinasa/metabolismo , Peróxido de Hidrógeno/metabolismo , Ácido Láctico/sangre , Masculino , Ventilación Voluntaria Máxima , Músculo Esquelético/metabolismo , Ratas , Ratas Wistar , Ácido Succínico , Factores de TiempoRESUMEN
Objective: Obesity and metabolic complications, such as type 2 diabetes and nonalcoholic fatty liver disease (NAFLD), are one of the greatest public health challenges of the 21st century. The major role of high sugar and carbohydrate consumption rather than caloric intake in obesity and NAFLD pathophysiology remains a subject of debate. A low-carbohydrate but high-fat diet (LCHFD) has shown promising results in obesity management, but its effects in preventing NAFLD need to be detailed. This study aims to compare the effects of a LCHFD with a high-fat high-sugar obesogenic Western diet (WD) on the progression of obesity, type 2 diabetes, and nonalcoholic fatty liver disease. Methods: Male C57BL/6J mice were initially fed a WD for 10 weeks. Subsequently, they were either switched to a LCHFD or maintained on the WD for an additional 6 weeks. Hepatic effects of the diet were explored by histological staining and RT-qPCR. Results: After the initial 10 weeks WD feeding, LCHF diet demonstrated effectiveness in halting weight gain, maintaining a normal glucose tolerance and insulin levels, in comparison to the WD-fed mice, which developed obesity, glucose intolerance, increased insulin levels and induced NAFLD. In the liver, LCHFD mitigated the accumulation of hepatic triglycerides and the increase in Fasn relative gene expression compared to the WD mice. Beneficial effects of the LCHFD occurred despite a similar calorie intake compared to the WD mice. Conclusion: Our results emphasize the negative impact of a high sugar/carbohydrate and lipid association for obesity progression and NAFLD development. LCHFD has shown beneficial effects for NAFLD management, notably improving weight management, and maintaining a normal glucose tolerance and liver health.
RESUMEN
Weight cycling is a major challenge in obesity management. Caloric restriction is known to promote this phenomenon, but the impact of macronutrient changes during dieting remains unclear. This study aimed to determine the role of macronutrient changes in weight maintenance without caloric restriction by alternating between two hypercaloric diets: a high-carbohydrate, high-fat Western diet (WD) and a low-carbohydrate, high-fat diet (LCHDF). Obesity was induced in 8-week-old C57BL/6 male mice by 10 weeks of WD feeding. Then, the mice were subjected to 12 weeks of LCHFD interspersed with WD (I-WD), 3 periods of 2-week LCHFD followed by 2 periods of 3-week WD, or 12 weeks of continuous WD (C-WD). C-WD and I-WD mice were compared to standard diet (SD) mice. In the I-WD group, each LCHFD period decreased weight gain, but mice regained weight after WD resumption. I-WD mice exhibited obesity, dyslipidemia, and glucose intolerance, similarly to the C-WD mice. I-WD mice also developed nonalcoholic steatohepatitis, associated with an increase in type-III collagen gene expression and a decrease in FGF21 protein levels, in comparison with SD. I-WD mice developed weight cycling despite maintaining a high caloric consumption, suggesting that changes in macronutrients during dieting are also a trigger of weight regain.
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Obesidad , Ciclo del Peso , Masculino , Ratones , Animales , Ratones Endogámicos C57BL , Obesidad/metabolismo , Modelos Animales de Enfermedad , Dieta Alta en Grasa , Nutrientes , Carbohidratos , Dieta Occidental , Hígado/metabolismoRESUMEN
Mutations in the DYNC1H1 gene encoding for dynein heavy chain cause two closely related human motor neuropathies, dominant spinal muscular atrophy with lower extremity predominance (SMA-LED) and axonal Charcot-Marie-Tooth (CMT) disease, and lead to sensory neuropathy and striatal atrophy in mutant mice. Dynein is the molecular motor carrying mitochondria retrogradely on microtubules, yet the consequences of dynein mutations on mitochondrial physiology have not been explored. Here, we show that mouse fibroblasts bearing heterozygous or homozygous point mutation in Dync1h1, similar to human mutations, show profoundly abnormal mitochondrial morphology associated with the loss of mitofusin 1. Furthermore, heterozygous Dync1h1 mutant mice display progressive mitochondrial dysfunction in muscle and mitochondria progressively increase in size and invade sarcomeres. As a likely consequence of systemic mitochondrial dysfunction, Dync1h1 mutant mice develop hyperinsulinemia and hyperglycemia and progress to glucose intolerance with age. Similar defects in mitochondrial morphology and mitofusin levels are observed in fibroblasts from patients with SMA-LED. Last, we show that Dync1h1 mutant fibroblasts show impaired perinuclear clustering of mitochondria in response to mitochondrial uncoupling. Our results show that dynein function is required for the maintenance of mitochondrial morphology and function with aging and suggest that mitochondrial dysfunction contributes to dynein-dependent neurological diseases, such as SMA-LED.
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Envejecimiento/patología , Dineínas Citoplasmáticas/genética , Mitocondrias/patología , Atrofia Muscular Espinal/genética , Atrofia Muscular Espinal/patología , Mutación/genética , Animales , Células Cultivadas , Embrión de Mamíferos , Femenino , Glucagón/sangre , Ácido Glutámico/genética , Humanos , Insulina/sangre , Lisina/genética , Masculino , Ratones , Ratones Endogámicos C57BL , Ratones Transgénicos , Mitocondrias/ultraestructura , Superóxido Dismutasa/metabolismo , Superóxido Dismutasa-1 , TransfecciónRESUMEN
Ageing is associated with skeletal muscle impairment. Changes in mitochondrial homeostasis are thought to play a key role in this process. This study examined whether chronic intake of polyphenols (PPs), which are known to be modulators of oxidative stress, might prevent the age-related decline of mitochondrial functions in skeletal muscle. Three groups of 10 Wistar rats were investigated. Rats aged 16 weeks were compared with rats aged 40 weeks that were given 75 mg kg(-1) day(-1) PPs or solvent in the drinking water starting at week 16. Mitochondrial respiratory chain complex activities were measured in saponin-skinned fibres of soleus muscles using glutamate-malate (V(max)), succinate (V(succ)) and N,N,N',N'-tetramethyl-p-phenylenediamine dihydrochloride-ascorbate (V(TMPD)). Production of reactive oxygen species was assessed using dihydroethidium staining. Transcript levels of genes involved in antioxidant defence were determined using RT-PCR. Ageing reduced muscle V(max) (from 8.8 ± 0.45 to 6.17 ± 0.51 µmol O(2) min(-1) g(-1), -30.5%, P < 0.01), V(TMPD) (from 20.67 ± 1.24 to 16.55 ± 1.16 µmol O(2) min(-1) g(-1), -19.9%, P < 0.05), increased production of reactive oxygen species (from 100 ± 9.9 to 351.1 ± 31.7%) and decreased transcripts of mitochondrial superoxide dismutase 2 (-59.3%, P < 0.01), peroxisome proliferator-activated receptor γ coactivator-1ß (PGC-1ß; -61.5%, P < 0.05) and sirtuin 1 (-54.2%, P < 0.05). Chronic PP intake normalized V(max) (8.63 ± 0.63 µmol O(2) min(-1) g(-1)), decreased production of reactive oxygen species (141.7 ± 16.7%, P < 0.001) and enhanced antioxidant defence (superoxide dismutase 2 expression, +151.3%, P < 0.05) and PGC-1ß expression (+185.7%, P < 0.05) in comparison to age-matched untreated rats. The present data indicate that regular intake of PPs starting at a young age prevents age-related mitochondrial respiratory impairment in skeletal muscle, probably through decreased oxidative stress and enhancement of PGC-1ß expression.
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Envejecimiento/metabolismo , Antioxidantes/farmacología , Metabolismo Energético/efectos de los fármacos , Mitocondrias Musculares/efectos de los fármacos , Músculo Esquelético/efectos de los fármacos , Estrés Oxidativo/efectos de los fármacos , Polifenoles/farmacología , Especies Reactivas de Oxígeno/metabolismo , Administración Oral , Factores de Edad , Animales , Antioxidantes/administración & dosificación , Ácido Ascórbico/metabolismo , Proteínas del Complejo de Cadena de Transporte de Electrón/metabolismo , Regulación de la Expresión Génica , Ácido Glutámico/metabolismo , Malatos/metabolismo , Masculino , Mitocondrias Musculares/metabolismo , Músculo Esquelético/metabolismo , Oxidación-Reducción , Coactivador 1-alfa del Receptor Activado por Proliferadores de Peroxisomas gamma , Polifenoles/administración & dosificación , ARN Mensajero/metabolismo , Proteínas de Unión al ARN/genética , Proteínas de Unión al ARN/metabolismo , Ratas , Ratas Wistar , Reacción en Cadena en Tiempo Real de la Polimerasa , Sirtuina 1/genética , Sirtuina 1/metabolismo , Ácido Succínico/metabolismo , Superóxido Dismutasa/genética , Superóxido Dismutasa/metabolismo , Factores de Tiempo , Factores de Transcripción/genética , Factores de Transcripción/metabolismoRESUMEN
Muscle dysfunction is a common complication and an important prognostic factor in chronic obstructive pulmonary disease (COPD). As therapeutic strategies are still needed to treat this complication, gaining more insight into the process that leads to skeletal muscle decline in COPD appears to be an important issue. This review focuses on mitochondrial involvement in limb skeletal muscle alterations (decreased muscle mass, strength, endurance and power and increased fatigue) in COPD. Mitochondria are the main source of energy for the cells; they are involved in production of reactive oxygen species and activate an important pathway that leads to apoptosis. In COPD patients, skeletal muscles are characterized by decreased mitochondrial density and biogenesis, impaired activity and coupling of mitochondrial respiratory chain complexes, increased mitochondrial production of reactive oxygen species and, possibly, increased apoptosis. Of particular interest, a sedentary lifestyle, hypoxia, hypercapnia, tobacco smoking, corticosteroid therapy and, possibly, inflammation participate in this mitochondrial dysfunction, which is accessible to conventional therapies, such as exercise and tobacco cessation, as well as, potentially, to more innovative approaches, such as antioxidant treatment and supplementation with polyunsaturated fatty acids.
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Mitocondrias Musculares/metabolismo , Mitocondrias Musculares/patología , Músculo Esquelético/fisiopatología , Enfermedad Pulmonar Obstructiva Crónica/fisiopatología , Animales , Humanos , Músculo Esquelético/metabolismo , Enfermedad Pulmonar Obstructiva Crónica/metabolismoRESUMEN
BACKGROUND: In contrast to mammalian erythrocytes, which have lost their nucleus and mitochondria during maturation, the erythrocytes of almost all other vertebrate species are nucleated throughout their lifespan. Little research has been done however to test for the presence and functionality of mitochondria in these cells, especially for birds. Here, we investigated those two points in erythrocytes of one common avian model: the zebra finch (Taeniopygia guttata). RESULTS: Transmission electron microscopy showed the presence of mitochondria in erythrocytes of this small passerine bird, especially after removal of haemoglobin interferences. High-resolution respirometry revealed increased or decreased rates of oxygen consumption by erythrocytes in response to the addition of respiratory chain substrates or inhibitors, respectively. Fluorometric assays confirmed the production of mitochondrial superoxide by avian erythrocytes. Interestingly, measurements of plasmatic oxidative markers indicated lower oxidative stress in blood of the zebra finch compared to a size-matched mammalian model, the mouse. CONCLUSIONS: Altogether, those findings demonstrate that avian erythrocytes possess functional mitochondria in terms of respiratory activities and reactive oxygen species (ROS) production. Interestingly, since blood oxidative stress was lower for our avian model compared to a size-matched mammalian, our results also challenge the idea that mitochondrial ROS production could have been one actor leading to this loss during the course of evolution. Opportunities to assess mitochondrial functioning in avian erythrocytes open new perspectives in the use of birds as models for longitudinal studies of ageing via lifelong blood sampling of the same subjects.
RESUMEN
We assessed the time courses of mitochondrial biogenesis factors and respiration in the right ventricle (RV), gastrocnemius (GAS), and left ventricle (LV) in a model of pulmonary-hypertensive rats. Monocrotaline (MT) rats and controls were studied 2 and 4 weeks after injection. Compensated and decompensated heart failure stages were defined according to obvious congestion signs. mRNA expression and protein level of peroxisome proliferator activated receptor gamma co-activator 1α (PGC-1α), citrate synthase (CS) mRNA and activity, and mitochondrial respiration were investigated. In addition, mRNA expression of sirtuin1, nuclear respiratory factor 1, and mitochondrial transcription factor A were studied. As early as 2 weeks, the expression of the studied genes was decreased in the MT GAS. At 4 weeks, the MT GAS and MT RV showed decreased mRNA levels whatever the stage of disease, but PGC-1α protein and CS activity were significantly reduced only at the decompensated stage. The functional result was a significant fall in mitochondrial respiration at the decompensated stage in the RV and GAS. The mRNA expression and mitochondrial respiration were not significantly modified in the MT LV. MT rats demonstrated an early decrease in expression of genes involved in mitochondrial biogenesis in a skeletal muscle, whereas reduced protein expression, and the resulting mitochondrial respiratory dysfunction appeared only in rats with overt heart failure, in the GAS and RV. Dissociations between mRNA and protein levels at the compensated stage deserve to be further studied.
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Ventrículos Cardíacos/fisiopatología , Hipertensión Pulmonar/fisiopatología , Mitocondrias Musculares/metabolismo , Disfunción Ventricular Derecha/fisiopatología , Animales , Citrato (si)-Sintasa/genética , Citrato (si)-Sintasa/metabolismo , Expresión Génica , Insuficiencia Cardíaca/enzimología , Insuficiencia Cardíaca/etiología , Insuficiencia Cardíaca/fisiopatología , Ventrículos Cardíacos/enzimología , Hipertensión Pulmonar/inducido químicamente , Hipertensión Pulmonar/complicaciones , Hipertensión Pulmonar/enzimología , Masculino , Monocrotalina , Músculo Esquelético/patología , Factor Nuclear 1 de Respiración/genética , Factor Nuclear 1 de Respiración/metabolismo , Consumo de Oxígeno , Coactivador 1-alfa del Receptor Activado por Proliferadores de Peroxisomas gamma , Proteínas de Unión al ARN/genética , Proteínas de Unión al ARN/metabolismo , Ratas , Ratas Wistar , Sirtuina 1/genética , Sirtuina 1/metabolismo , Factores de Transcripción/genética , Factores de Transcripción/metabolismo , Disfunción Ventricular Derecha/enzimología , Disfunción Ventricular Derecha/etiologíaRESUMEN
Atherosclerosis is an immunoinflammatory disease elicited by accumulation of lipids in the artery wall and leads to myocardial infarction and stroke. Here, we show that naturally arising CD4(+)CD25(+) regulatory T cells, which actively maintain immunological tolerance to self and nonself antigens, are powerful inhibitors of atherosclerosis in several mouse models. These results provide new insights into the immunopathogenesis of atherosclerosis and could lead to new therapeutic approaches that involve immune modulation using regulatory T cells.
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Aterosclerosis/etiología , Linfocitos T Reguladores/inmunología , Animales , Apolipoproteínas E/deficiencia , Apolipoproteínas E/genética , Aterosclerosis/inmunología , Aterosclerosis/patología , Antígeno B7-1/genética , Antígenos CD28/genética , Proteínas de Unión al ADN/deficiencia , Proteínas de Unión al ADN/genética , Femenino , Inmunidad Innata , Ratones , Ratones Endogámicos C57BL , Ratones Noqueados , Linfocitos T Reguladores/patologíaRESUMEN
AIMS: Statins protect against cardiovascular-related mortality but induce skeletal muscle toxicity. To investigate mechanisms of statins, we tested the hypothesis that statins optimized cardiac mitochondrial function but impaired vulnerable skeletal muscle by inducing different level of reactive oxygen species (ROS). METHODS AND RESULTS: In atrium of patients treated with statins, ROS production was decreased and oxidative capacities were enhanced together with an extensive augmentation of mRNAs expression of peroxisome proliferator-activated receptor gamma co-activator (PGC-1) family. However, in deltoid biopsies from patients with statin-induced muscular myopathy, oxidative capacities were decreased together with ROS increase and a collapse of PGC-1 mRNA expression. Several animal and cell culture experiments were conducted and showed by using ROS scavengers that ROS production was the triggering factor responsible of atorvastatin-induced activation of mitochondrial biogenesis pathway and improvement of antioxidant capacities in heart. Conversely, in skeletal muscle, the large augmentation of ROS production following treatment induced mitochondrial impairments, and reduced mitochondrial biogenesis mechanisms. Quercetin, an antioxidant molecule, was able to counteract skeletal muscle deleterious effects of atorvastatin in rat. CONCLUSION: Our findings identify statins as a new activating factor of cardiac mitochondrial biogenesis and antioxidant capacities, and suggest the importance of ROS/PGC-1 signalling pathway as a key element in regulation of mitochondrial function in cardiac as well as skeletal muscles.
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Ácidos Heptanoicos/farmacología , Inhibidores de Hidroximetilglutaril-CoA Reductasas/farmacología , Mitocondrias Musculares/efectos de los fármacos , Músculo Esquelético/efectos de los fármacos , Pirroles/farmacología , Especies Reactivas de Oxígeno/metabolismo , Factores de Transcripción/metabolismo , Animales , Antioxidantes/farmacología , Atorvastatina , Atrios Cardíacos , Humanos , Masculino , Mitocondrias Cardíacas/efectos de los fármacos , Fibras Musculares Esqueléticas/efectos de los fármacos , Fibras Musculares Esqueléticas/metabolismo , Miocitos Cardíacos/efectos de los fármacos , Miocitos Cardíacos/metabolismo , Quercetina/farmacología , ARN Mensajero/metabolismo , Ratas , Ratas Wistar , Superóxido Dismutasa/farmacologíaRESUMEN
Alzheimer's disease (AD) is a neurodegenerative disease that affects almost 1 million people in France and 55 million in the world. This pathology is a global health preoccupation because of the lack of efficient curative treatment and the increase of its prevalence. During the last decade, the comprehension of pathophysiological mechanisms involved in AD have been improved. Amyloid plaques and neurofibrillary tangles accumulation are characteristic of Alzheimer's brain patients, accompanied by increased brain inflammation and oxidative stress, impaired cerebral metabolism of glucose and mitochondrial function. Treatment of AD includes different approaches, as pharmacology, psychology support, physiotherapy, and speech therapy. However, these interventions do not have a curative effect, but only compensatory on the disease. Ketogenic diet (KD), a low-carbohydrates and high-fat diet, associated with a medium-chain triglycerides intake (MCTs) might induce benefices for Alzheimer disease patients. Carbohydrate restriction and MCTs promotes the production of ketone bodies from fatty acid degradation. These metabolites replacing glucose, serve the brain as energetic substrates, and induce neuroprotective effects. Such a nutritional support might slow down the disease progression and improve cognitive abilities of patients. This review aims to examine the neuroprotective mechanisms of KD in AD progression and describes the advantages and limitations of KD as a therapeutic strategy.
Title: Intérêt du régime cétogène dans la prise en charge de la maladie d'Alzheimer. Abstract: La maladie d'Alzheimer (MA), pathologie neurodégénérative en expansion, devient une préoccupation importante de santé publique, en raison d'une absence de traitement curatif efficace. Les mécanismes mis en Åuvre dans la physiopathologie de la MA sont de mieux en mieux connus, et incluent l'accumulation de plaques amyloïdes et de dégénérescences neurofibrillaires. L'augmentation de l'inflammation et du stress oxydant et l'altération du métabolisme cérébral du glucose aggravent la pathologie en réduisant l'activité neuronale en perturbant la fonction mitochondriale. À l'heure actuelle, le traitement de cette pathologie regroupe différentes approches bien que ces interventions n'aient pas un effet curatif, mais uniquement compensatoire. L'alimentation cétogène, pauvre en glucides et enrichie en lipides, couplée à une prise de triglycérides à chaîne moyenne (MCT), favorise la production de corps cétoniques, substrats énergétiques qui pourraient présenter des effets neuroprotecteurs bénéfiques pour les personnes atteintes de la MA. Une telle prise en charge nutritionnelle pourrait limiter la progression de la maladie et améliorer les capacités cognitives des patients. Cette revue vise à examiner le rôle éventuel et les mécanismes neuroprotecteurs de l'alimentation cétogène dans la progression de la MA, et décrit les avantages et les limites de son utilisation comme stratégie thérapeutique.