RESUMO
The high capacity of the skeletal muscle to regenerate is due to the presence of muscle stem cells (MuSCs, or satellite cells). The E3 ubiquitin ligase Parkin is a key regulator of mitophagy and is recruited to mitochondria during differentiation of mouse myoblast cell line. However, the function of mitophagy during regeneration has not been investigated in vivo. Here, we have utilized Parkin deficient (Parkin-/-) mice to investigate the role of Parkin in skeletal muscle regeneration. We found a persistent deficiency in skeletal muscle regeneration in Parkin-/- mice after cardiotoxin (CTX) injury with increased area of fibrosis and decreased cross-sectional area (CSA) of myofibres post-injury. There was also a significant modulation of MuSCs differentiation and mitophagic markers, with altered mitochondrial proteins during skeletal muscle regeneration in Parkin-/- mice. Our data suggest that Parkin-mediated mitophagy plays a key role in skeletal muscle regeneration and is necessary for MuSCs differentiation.
Assuntos
Diferenciação Celular , Mitocôndrias/patologia , Proteínas Mitocondriais/metabolismo , Desenvolvimento Muscular , Músculo Esquelético/patologia , Regeneração , Ubiquitina-Proteína Ligases/fisiologia , Animais , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Mitocôndrias/metabolismo , Mitofagia , Músculo Esquelético/metabolismo , Células-Tronco/citologiaRESUMO
PURPOSE: Nicotinamide riboside (NR) acts as a potent NAD+ precursor and improves mitochondrial oxidative capacity and mitochondrial biogenesis in several organisms. However, the effects of NR supplementation on aerobic performance remain unclear. Here, we evaluated the effects of NR supplementation on the muscle metabolism and aerobic capacity of sedentary and trained mice. METHODS: Male C57BL/6 J mice were supplemented with NR (400 mg/Kg/day) over 5 and 10 weeks. The training protocol consisted of 5 weeks of treadmill aerobic exercise, for 60 min a day, 5 days a week. Bioinformatic and physiological assays were combined with biochemical and molecular assays to evaluate the experimental groups. RESULTS: NR supplementation by itself did not change the aerobic performance, even though 5 weeks of NR supplementation increased NAD+ levels in the skeletal muscle. However, combining NR supplementation and aerobic training increased the aerobic performance compared to the trained group. This was accompanied by an increased protein content of NMNAT3, the rate-limiting enzyme for NAD + biosynthesis and mitochondrial proteins, including MTCO1 and ATP5a. Interestingly, the transcriptomic analysis using a large panel of isogenic strains of BXD mice confirmed that the Nmnat3 gene in the skeletal muscle is correlated with several mitochondrial markers and with different phenotypes related to physical exercise. Finally, NR supplementation during aerobic training markedly increased the amount of type I fibers in the skeletal muscle. CONCLUSION: Taken together, our results indicate that NR may be an interesting strategy to improve mitochondrial metabolism and aerobic capacity.
Assuntos
Aerobiose/efeitos dos fármacos , Mitocôndrias/efeitos dos fármacos , Mitocôndrias/metabolismo , NAD/metabolismo , Niacinamida/análogos & derivados , Compostos de Piridínio/metabolismo , Compostos de Piridínio/farmacologia , Animais , Respiração Celular/efeitos dos fármacos , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Músculo Esquelético/efeitos dos fármacos , Músculo Esquelético/metabolismo , Niacinamida/metabolismo , Niacinamida/farmacologiaRESUMO
We aimed to investigate the mechanisms underlying muscle growth after 12 weeks of resistance training performed with blood flow restriction (RT-BFR) and high-intensity resistance training (HRT) in older individuals. Participants were allocated into the following groups: HRT, RT-BFR, or a control group. High-throughput transcriptome sequencing was performed by the Illumina HiSeq 2500 platform. HRT and RT-BFR presented similar increases in the quadriceps femoris cross-sectional area, and few genes were differently expressed between interventions. The small differences in gene expression between interventions suggest that similar mechanisms may underpin training-induced muscle growth.
Assuntos
Envelhecimento/fisiologia , Músculo Esquelético/metabolismo , Educação Física e Treinamento , Fluxo Sanguíneo Regional/fisiologia , Treinamento Resistido , Transcriptoma/fisiologia , Idoso , DNA/biossíntese , DNA/genética , Dieta , Feminino , Regulação da Expressão Gênica/fisiologia , Humanos , Perna (Membro)/anatomia & histologia , Perna (Membro)/fisiologia , Masculino , Pessoa de Meia-Idade , Músculo Esquelético/irrigação sanguínea , Músculo Quadríceps/fisiologia , RNA/biossíntese , RNA/genéticaRESUMO
Here we evaluated the effect of fermented milk supplemented with whey protein (approximately 80 % protein), probiotic (Bifidobacterium animalis subsp. lactis BB12) and pomegranate juice (Punica granatum L.) on the physical performance, intestinal motility and villi structure, inflammatory markers and intestinal microbiota of rats under high-intensity acute exercise. In all, twenty-four Wistar rats were separated into groups: control (Ctrl), supplemented (Supp), exercised (Exe) and exercised and supplemented (Exe+Supp). Rats in the Supp groups received fermented milk during 6 weeks by oral administration. At the end of the supplementation period, the Exe groups were submitted to high-intensity acute exercise on a treadmill. We found that intense acute exercise caused changes in the intestinal villi interspace, changes in the proportion of Lactobacillus species and an increase in Clostridium species, as well as a decrease in intestinal motility. Supplementation increased intestinal motility, and maintained the intestinal villi interspace and the natural microbiota proportions of the exercised rats. Physical performance was not improved by fermented milk supplementation. We conclude that the fermented milk containing whey protein, B. animalis (BB12) and pomegranate juice can re-establish intestinal microbiota and protect the animals from the undesirable effects of intense acute exercise.
Assuntos
Bifidobacterium animalis , Sucos de Frutas e Vegetais , Lythraceae , Probióticos , Proteínas do Soro do Leite/administração & dosagem , Animais , Produtos Fermentados do Leite , Intestinos/efeitos dos fármacos , Masculino , Leite , Condicionamento Físico Animal , Ratos , Ratos Wistar , Proteínas do Soro do Leite/farmacologiaRESUMO
The accumulation of fatty acids in the liver associated with obesity condition is also known as nonalcoholic fatty liver disease (NAFLD). The impaired fat oxidation in obesity condition leads to increased hepatic fat accumulation and increased metabolic syndrome risk. On the other hand, physical exercise has been demonstrated as a potent strategy in the prevention of NAFLD. Also, these beneficial effects of exercise occur through different mechanisms. Recently, the Cdc2-like kinase (CLK2) protein was associated with the suppression of fatty acid oxidation and hepatic ketogenesis. Thus, obese animals demonstrated elevated levels of hepatic CLK2 and decreased fat acid oxidation. Here, we explored the effects of chronic physical exercise in the hepatic metabolism of obese mice. Swiss mice were distributed in Lean, Obese (fed with high-fat diet during 16 weeks) and Trained Obese group (fed with high-fat diet during 16 weeks and exercised (at 60% exhaustion velocity during 1 h/5 days/week) during 8 weeks. In our results, the obese animals showed insulin resistance, increased hepatic CLK2 content and increased hepatic fat accumulation compared to the Lean group. Otherwise, the chronic physical exercise improved insulin resistance state, prevented the increased CLK2 in the liver and attenuated hepatic fat accumulation. In summary, these data reveal a new protein involved in the prevention of hepatic fat accumulation after chronic physical exercise. More studies can evidence the negative role of CLK2 in the control of liver metabolism, contributing to the improvement of insulin resistance, obesity, and type 2 diabetes.
Assuntos
Resistência à Insulina , Lipogênese , Fígado/enzimologia , Obesidade/terapia , Condicionamento Físico Animal , Proteínas Serina-Treonina Quinases/metabolismo , Proteínas Tirosina Quinases/metabolismo , Magreza/fisiopatologia , Animais , Dieta Hiperlipídica/efeitos adversos , Metabolismo dos Lipídeos , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Obesos , Obesidade/enzimologia , Obesidade/etiologia , Proteínas Serina-Treonina Quinases/genética , Proteínas Tirosina Quinases/genéticaRESUMO
The effects of physical exercise on insulin signaling and glycemic homeostasis are not yet fully understood. Recent findings elucidated the positive role of Rho-kinase (Rock) in increasing the glucose uptake through insulin receptor substrate-1 (IRS1) phosphorylation in the skeletal muscle. Here, we explored the effects of short-term exercise on Rock activity and insulin signaling. Fischer 344 rats (3 months old) were subjected to a short-term swimming exercise for 2 hr per day for 5 days, with an overload corresponding to 1.5% of body weight. As expected, the exercised group had a reduced glycemia and increased insulin sensitivity. The contents of Rock1, Rock2, and Rock activity were improved in the skeletal muscle of the exercised rats. The contents of RhoA and RhoGEF, which are proteins involved in the Rock metabolism, were also increased in the skeletal muscle after exercise. These changes in the protein contents were accompanied by an increase in the insulin signaling pathway (pIRS1/pPDK/pAkt/pGSK3ß/pAS160/GLUT4), Rock activity, and IRS1 phosphorylation at the 632/635 serine residues. On the other hand, when Rock was inhibited with the Y-27632, the insulin sensitivity in response to exercise was impaired. Based on these findings, we conclude that the short-term exercise increased both insulin sensitivity and glucose tolerance, through the increased Rock activity and pIRS1 (serine 632/635) mediated by Rock, in the skeletal muscle of Fischer 344 rats. These data represent an exercise-mediated novel mechanism, suggesting an essential role of Rock activity in the insulin signaling and glucose homeostasis improvement.
Assuntos
Insulina/metabolismo , Contração Muscular , Músculo Esquelético/enzimologia , Condicionamento Físico Animal , Esforço Físico , Quinases Associadas a rho/metabolismo , Animais , Glicemia/metabolismo , Transportador de Glucose Tipo 4/metabolismo , Proteínas Substratos do Receptor de Insulina/metabolismo , Resistência à Insulina , Masculino , Fosforilação , Ratos Endogâmicos F344 , Transdução de Sinais , Natação , Fatores de TempoRESUMO
Our aim is to gain insight into the mechanisms underlying the anti-atrophic effects of leucine, namely, the way that this amino acid can restrain the up-regulation of MuRF1 and Mafbx/Atrogin-1 in muscle atrophy. Male rats received dietary leucine supplementation for 1-3 days, during which time their hind limbs were immobilized. Our results showed that leucine inhibited Forkhead Box O3 (FoxO3a) translocation to cell nuclei. In addition, leucine was able to reverse the expected reduction of FoXO3a ubiquitination caused by immobilization. Unexpectedly, leucine promoted these effects independently of the Class I PI3K/Akt pathway. Vacuolar protein sorting 34 (VPS34; a Class III PI3K) was strongly localized in nuclei after immobilization and leucine supplementation was able to prevent this effect. In experiments on cultured primary myotubes, dexamethasone led to the localization of VPS34 in the nucleus. In addition, the pharmacological inhibition of VPS34 blocked VPS34 nuclear localization and impaired the protective effect of leucine upon myotube trophicity. Finally, the pharmacological inhibition of VPS34 in primary myotubes prevented the protective effects of leucine upon MuRF1 and Mafbx/Atrogin-1 gene expression. Autophagy-related target genes were not responsive to leucine. Thus, we demonstrate that the anti-atrophic effect of leucine is dependent upon FoxO3a suppression and VPS34 activity.
Assuntos
Classe III de Fosfatidilinositol 3-Quinases/metabolismo , Proteína Forkhead Box O3/metabolismo , Leucina/farmacologia , Músculo Esquelético/patologia , Atrofia Muscular/patologia , Animais , Núcleo Celular/efeitos dos fármacos , Núcleo Celular/metabolismo , Dexametasona/farmacologia , Masculino , Fibras Musculares Esqueléticas/efeitos dos fármacos , Fibras Musculares Esqueléticas/metabolismo , Músculo Esquelético/efeitos dos fármacos , Proteínas Proto-Oncogênicas c-akt/metabolismo , Ratos Wistar , UbiquitinaçãoRESUMO
This study was undertaken in order to provide further insight into the role of leucine supplementation in the skeletal muscle regeneration process, focusing on myofiber size and strength recovery. Young (2-month-old) rats were subjected or not to leucine supplementation (1.35 g/kg per day) started 3 days prior to cryolesion. Then, soleus muscles were cryolesioned and continued receiving leucine supplementation until 1, 3 and 10 days later. Soleus muscles from leucine-supplemented animals displayed an increase in myofiber size and a reduction in collagen type III expression on post-cryolesion day 10. Leucine was also effective in reducing FOXO3a activation and ubiquitinated protein accumulation in muscles at post-cryolesion days 3 and 10. In addition, leucine supplementation minimized the cryolesion-induced decrease in tetanic strength and increase in fatigue in regenerating muscles at post-cryolesion day 10. These beneficial effects of leucine were not accompanied by activation of any elements of the phosphoinositide 3-kinase/Akt/mechanistic target of rapamycin signalling pathway in the regenerating muscles. Our results show that leucine improves myofiber size gain and strength recovery in regenerating soleus muscles through attenuation of protein ubiquitination. In addition, leucine might have therapeutic effects for muscle recovery following injury and in some muscle diseases.
Assuntos
Suplementos Nutricionais , Leucina/administração & dosagem , Músculo Esquelético/efeitos dos fármacos , Distrofias Musculares/dietoterapia , Regeneração/efeitos dos fármacos , Proteínas Quinases Dependentes de 3-Fosfoinositídeo/genética , Proteínas Quinases Dependentes de 3-Fosfoinositídeo/metabolismo , Administração Oral , Animais , Temperatura Baixa , Proteína Forkhead Box O3 , Fatores de Transcrição Forkhead/genética , Fatores de Transcrição Forkhead/metabolismo , Expressão Gênica , Membro Posterior , Masculino , Contração Muscular/efeitos dos fármacos , Músculo Esquelético/lesões , Músculo Esquelético/metabolismo , Distrofias Musculares/genética , Distrofias Musculares/metabolismo , Proteínas Proto-Oncogênicas c-akt/genética , Proteínas Proto-Oncogênicas c-akt/metabolismo , Ratos , Ratos Wistar , Transdução de Sinais , Serina-Treonina Quinases TOR/genética , Serina-Treonina Quinases TOR/metabolismo , Ubiquitinação/efeitos dos fármacosRESUMO
In the present study we have compared the effects of leucine supplementation and its metabolite ß-hydroxy-ß-methyl butyrate (HMB) on the ubiquitin-proteasome system and the PI3K/Akt pathway during two distinct atrophic conditions, hindlimb immobilization and dexamethasone treatment. Leucine supplementation was able to minimize the reduction in rat soleus mass driven by immobilization. On the other hand, leucine supplementation was unable to provide protection against soleus mass loss in dexamethasone treated rats. Interestingly, HMB supplementation was unable to provide protection against mass loss in all treatments. While solely fiber type I cross sectional area (CSA) was protected in immobilized soleus of leucine-supplemented rats, none of the fiber types were protected by leucine supplementation in rats under dexamethasone treatment. In addition and in line with muscle mass results, HMB treatment did not attenuate CSA decrease in all fiber types against either immobilization or dexamethasone treatment. While leucine supplementation was able to minimize increased expression of both Mafbx/Atrogin and MuRF1 in immobilized rats, leucine was only able to minimize Mafbx/Atrogin in dexamethasone treated rats. In contrast, HMB was unable to restrain the increase in those atrogenes in immobilized rats, but in dexamethasone treated rats, HMB minimized increased expression of Mafbx/Atrogin. The amount of ubiquitinated proteins, as expected, was increased in immobilized and dexamethasone treated rats and only leucine was able to block this increase in immobilized rats but not in dexamethasone treated rats. Leucine supplementation maintained soleus tetanic peak force in immobilized rats at normal level. On the other hand, HMB treatment failed to maintain tetanic peak force regardless of treatment. The present data suggested that the anti-atrophic effects of leucine are not mediated by its metabolite HMB.
Assuntos
Suplementos Nutricionais , Leucina/administração & dosagem , Músculo Esquelético/efeitos dos fármacos , Músculo Esquelético/metabolismo , Complexo de Endopeptidases do Proteassoma/metabolismo , Sarcopenia/metabolismo , Valeratos/administração & dosagem , Animais , Elevação dos Membros Posteriores/efeitos adversos , Masculino , Músculo Esquelético/patologia , Tamanho do Órgão/efeitos dos fármacos , Fosfatidilinositol 3-Quinases/metabolismo , Proteínas Proto-Oncogênicas c-akt/metabolismo , Ratos , Sarcopenia/tratamento farmacológico , Sarcopenia/patologiaRESUMO
OBJECTIVE: The aim of this study was to assess the mRNA levels of atrogin-1, muscle ring finger 1, and myostatin in rat quadriceps after anterior cruciate ligament (ACL) transection. DESIGN: Wistar rats were randomized into three different groups: ACL (surgery and ACL transection), sham (surgery without ACL transection), and control. Vastus medialis, rectus femoris, and vastus lateralis muscles were harvested at 1, 2, 3, 7, and 15 days after ACL transection. The mRNA levels of atrogin-1, muscle ring finger 1, and myostatin, as well as the ubiquitinated protein content, muscle mass, and cross-sectional area of the muscle fibers, were evaluated. RESULTS: Elevated levels of atrogin-1, muscle ring finger 1, and myostatin mRNA were detected in all tested muscles at most time points. The ubiquitinated protein content was increased at 3 days in the ACL and sham groups. The muscle mass of the ACL group was reduced at 3, 7, and 15 days (vastus lateralis and vastus medialis) and at 7 and 15 days (rectus femoris), whereas it was reduced in the sham group at 3 and 7 days (vastus lateralis and vastus medialis) and at 7 days (rectus femoris). The cross-sectional area of vastus medialis was reduced at 3, 7, and 15 days in the ACL group and at 3 and 7 days in the sham group. The cross-sectional area of the vastus lateralis was reduced at 7 and 15 days in the ACL group and at 7 days in the sham group. Whereas muscle mass and cross-sectional area recovery was noted in the sham group, no recovery was observed in the ACL group. CONCLUSIONS: Quadriceps atrophy after ACL transection involves increased levels of myostatin, atrogin-1, and muscle ring finger 1 mRNA and the accumulation of ubiquitinated protein.