Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 2.808
Filtrar
1.
PLoS One ; 15(11): e0242422, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-33237943

RESUMO

Statins are used to lower cholesterol and prevent cardiovascular disease. Musculoskeletal side effects known as statin associated musculoskeletal symptoms (SAMS), are reported in up to 10% of statin users, necessitating statin therapy interruption and increasing cardiovascular disease risk. We tested the hypothesis that, when exposed to statins ex vivo, engineered human skeletal myobundles derived from individuals with (n = 10) or without (n = 14) SAMS and elevated creatine-kinase levels exhibit statin-dependent muscle defects. Myoblasts were derived from muscle biopsies of individuals (median age range of 62-64) with hyperlipidemia with (n = 10) or without (n = 14) SAMS. Myobundles formed from myoblasts were cultured with growth media for 4 days, low amino acid differentiation media for 4 days, then dosed with 0 and 5µM of statins for 5 days. Tetanus forces were subsequently measured. To model the change of tetanus forces among clinical covariates, a mixed effect model with fixed effects being donor type, statin concentration, statin type and their two way interactions (donor type*statin concentration and donor type* statin type) and the random effect being subject ID was applied. The results indicate that statin exposure significantly contributed to decrease in force (P<0.001) and the variability in data (R2C [R square conditional] = 0.62). We found no significant differences in force between myobundles from patients with/without SAMS, many of whom had chronic diseases. Immunofluorescence quantification revealed a positive correlation between the number of straited muscle fibers and tetanus force (R2 = 0.81,P = 0.015) and negative correlation between number of fragmented muscle fibers and tetanus force (R2 = 0.482,P = 0.051) with no differences between donors with or without SAMS. There is also a correlation between statin exposure and presence of striated fibers (R2 = 0.833, P = 0.047). In patient-derived myobundles, statin exposure results in myotoxicity disrupting SAA organization and reducing force. We were unable to identify differences in ex vivo statin myotoxicity in this system. The results suggest that it is unlikely that there is inherent susceptibility to or persistent effects of statin myopathy using patient-derived myobundles.


Assuntos
Inibidores de Hidroximetilglutaril-CoA Redutases/toxicidade , Músculo Esquelético/efeitos dos fármacos , Doenças Musculares/induzido quimicamente , Idoso , Aminoácidos/farmacologia , Células Cultivadas , Meios de Cultura/farmacologia , Feminino , Humanos , Inibidores de Hidroximetilglutaril-CoA Redutases/administração & dosagem , Inibidores de Hidroximetilglutaril-CoA Redutases/uso terapêutico , Hiperlipidemias/tratamento farmacológico , Hiperlipidemias/patologia , Técnicas In Vitro , Masculino , Pessoa de Meia-Idade , Contração Muscular/efeitos dos fármacos , Fadiga Muscular/fisiologia , Fibras Musculares Esqueléticas/efeitos dos fármacos , Fibras Musculares Esqueléticas/fisiologia , Músculo Esquelético/fisiopatologia , Doenças Musculares/fisiopatologia , Mioblastos/efeitos dos fármacos , Músculo Quadríceps/citologia , Método Simples-Cego , Engenharia Tecidual
2.
Sci Rep ; 10(1): 13305, 2020 08 06.
Artigo em Inglês | MEDLINE | ID: mdl-32764726

RESUMO

Cellular self-organization is the fundamental driving force behind the complex architectures of native tissue. Yet, attempts at replicating native tissue architectures in vitro often involve complex micro-fabrication methods and materials. While impressive progress has been made within engineered models of striated muscle, the wide adaptation of these models is held back by the need for specific tools and knowhow. In this report, we show that C2C12 myoblasts spontaneously organize into highly aligned myotube tissues on the mm to cm scale, when cultured on sufficiently soft yet fully isotropic gelatin hydrogel substrates. Interestingly, we only observed this phenomenon for hydrogels with Young's modulus of 6 kPa and below. For slightly more rigid compositions, only local micrometer-scale myotube organization was observed, similar to that seen in conventional polystyrene dishes. The hydrogel-supported myotubes could be cultured for multiple weeks and matured into highly contractile phenotypes with notable upregulation of myosin heavy chain, as compared to myotubes developed in conventional petri dishes. The procedure for casting the ultra-soft gelatin hydrogels is straight forward and compatible with standardized laboratory tools. It may thus serve as a simple, yet versatile, approach to generating skeletal muscle tissue of improved physiological relevance for applied and basic research.


Assuntos
Gelatina/química , Gelatina/farmacologia , Hidrogéis , Fenômenos Mecânicos , Músculo Esquelético/citologia , Músculo Esquelético/efeitos dos fármacos , Animais , Fenômenos Biomecânicos/efeitos dos fármacos , Camundongos , Fibras Musculares Esqueléticas/citologia , Fibras Musculares Esqueléticas/efeitos dos fármacos , Mioblastos/citologia , Mioblastos/efeitos dos fármacos , Engenharia Tecidual
3.
Am J Physiol Regul Integr Comp Physiol ; 319(4): R439-R447, 2020 10 01.
Artigo em Inglês | MEDLINE | ID: mdl-32847398

RESUMO

Cold exposure depolarizes cells in insects due to a reduced electrogenic ion transport and a gradual increase in extracellular K+ concentration ([K+]). Cold-induced depolarization is linked to cold injury in chill-susceptible insects, and the locust, Locusta migratoria, has been shown to improve cold tolerance following cold acclimation through depolarization resistance. Here we investigate how cold acclimation influences depolarization resistance and how this resistance relates to improved cold tolerance. To address this question, we investigated if cold acclimation affects the electrogenic transport capacity and/or the relative K+ permeability during cold exposure by measuring membrane potentials of warm- and cold-acclimated locusts in the presence and absence of ouabain (Na+-K+ pump blocker) or 4-aminopyridine (4-AP; voltage-gated K+ channel blocker). In addition, we compared the membrane lipid composition of muscle tissue from warm- and cold-acclimated locust and the abundance of a range transcripts related to ion transport and cell injury accumulation. We found that cold-acclimated locusts are depolarization resistant due to an elevated K+ permeability, facilitated by opening of 4-AP-sensitive K+ channels. In accordance, cold acclimation was associated with an increased abundance of Shaker transcripts (gene encoding 4-AP-sensitive voltage-gated K+ channels). Furthermore, we found that cold acclimation improved muscle cell viability following exposure to cold and hyperkalemia even when muscles were depolarized substantially. Thus cold acclimation confers resistance to depolarization by altering the relative ion permeability, but cold-acclimated locusts are also more tolerant to depolarization.


Assuntos
Aclimatação/fisiologia , Temperatura Baixa , Locusta migratoria/fisiologia , Fibras Musculares Esqueléticas/fisiologia , 4-Aminopiridina/farmacologia , Aclimatação/efeitos dos fármacos , Animais , Potenciais da Membrana/efeitos dos fármacos , Potenciais da Membrana/fisiologia , Fibras Musculares Esqueléticas/efeitos dos fármacos , Ouabaína/farmacologia
4.
PLoS One ; 15(8): e0236164, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32760085

RESUMO

Hyaluronan (HA) is a nonsulfated glycosaminoglycan that has been widely used for biomedical applications. Here, we have analyzed the effect of HA on the rescue of primary cells under stress as well as its potential to recover muscle atrophy and validated the developed model in vitro using primary muscle cells derived from rats. The potentials of different HAs were elucidated through comparative analyses using pharmaceutical grade a) high (HHA) and b) low molecular weight (LHA) hyaluronans, c) hybrid cooperative complexes (HCC) of HA in three experimental set-ups. The cells were characterized based on the expression of myogenin, a muscle-specific biomarker, and the proliferation was analyzed using Time-Lapse Video Microscopy (TLVM). Cell viability in response to H2O2 challenge was evaluated by 3-[4,5-dimethylthiazole-2-yl]-2,5-diphenyltetrazolium bromide (MTT) assay, and the expression of the superoxide dismutase enzyme (SOD-2) was assessed by western blotting. Additionally, in order to establish an in vitro model of atrophy, muscle cells were treated with tumor necrosis factor-alpha (TNF-α), along with hyaluronans. The expression of Atrogin, MuRF-1, nuclear factor kappa-light-chain-enhancer of activated B-cells (NF-kB), and Forkhead-box-(Fox)-O-3 (FoxO3a) was evaluated by western blotting to elucidate the molecular mechanism of atrophy. The results showed that HCC and HHA increased cell proliferation by 1.15 and 2.3 folds in comparison to un-treated cells (control), respectively. Moreover, both pre- and post-treatments of HAs restored the cell viability, and the SOD-2 expression was found to be reduced by 1.5 fold in HA-treated cells as compared to the stressed condition. Specifically in atrophic stressed cells, HCC revealed a noteworthy beneficial effect on the myogenic biomarkers indicating that it could be used as a promising platform for tissue regeneration with specific attention to muscle cell protection against stressful agents.


Assuntos
Ácido Hialurônico/farmacologia , Fibras Musculares Esqueléticas/efeitos dos fármacos , Atrofia Muscular/terapia , Medicina Regenerativa/métodos , Animais , Proliferação de Células/efeitos dos fármacos , Sobrevivência Celular/efeitos dos fármacos , Meios de Cultura/metabolismo , Géis , Humanos , Ácido Hialurônico/química , Peróxido de Hidrogênio/toxicidade , Microscopia Intravital , Peso Molecular , Fibras Musculares Esqueléticas/patologia , Atrofia Muscular/patologia , Miogenina/análise , Miogenina/metabolismo , Estresse Oxidativo/efeitos dos fármacos , Cultura Primária de Células , Ratos , Superóxido Dismutase/análise , Superóxido Dismutase/metabolismo , Imagem com Lapso de Tempo , Fator de Necrose Tumoral alfa/metabolismo
5.
Sci Rep ; 10(1): 14175, 2020 08 25.
Artigo em Inglês | MEDLINE | ID: mdl-32843714

RESUMO

Patients with chronic kidney disease (CKD) are often 25(OH)D3 and 1,25(OH)2D3 insufficient. We studied whether vitamin D repletion could correct aberrant adipose tissue and muscle metabolism in a mouse model of CKD-associated cachexia. Intraperitoneal administration of 25(OH)D3 and 1,25(OH)2D3 (75 µg/kg/day and 60 ng/kg/day respectively for 6 weeks) normalized serum concentrations of 25(OH)D3 and 1,25(OH)2D3 in CKD mice. Vitamin D repletion stimulated appetite, normalized weight gain, and improved fat and lean mass content in CKD mice. Vitamin D supplementation attenuated expression of key molecules involved in adipose tissue browning and ameliorated expression of thermogenic genes in adipose tissue and skeletal muscle in CKD mice. Furthermore, repletion of vitamin D improved skeletal muscle fiber size and in vivo muscle function, normalized muscle collagen content and attenuated muscle fat infiltration as well as pathogenetic molecular pathways related to muscle mass regulation in CKD mice. RNAseq analysis was performed on the gastrocnemius muscle. Ingenuity Pathway Analysis revealed that the top 12 differentially expressed genes in CKD were correlated with impaired muscle and neuron regeneration, enhanced muscle thermogenesis and fibrosis. Importantly, vitamin D repletion normalized the expression of those 12 genes in CKD mice. Vitamin D repletion may be an effective therapeutic strategy for adipose tissue browning and muscle wasting in CKD patients.


Assuntos
Adipócitos Bege/efeitos dos fármacos , Caquexia/tratamento farmacológico , Calcifediol/uso terapêutico , Calcitriol/uso terapêutico , Insuficiência Renal Crônica/complicações , Adipócitos Bege/metabolismo , Adipócitos Marrons/metabolismo , Adipócitos Brancos/metabolismo , Animais , Caquexia/etiologia , Caquexia/fisiopatologia , Calcifediol/sangue , Calcifediol/deficiência , Calcifediol/farmacologia , Calcitriol/sangue , Calcitriol/deficiência , Calcitriol/farmacologia , Modelos Animais de Doenças , Ingestão de Alimentos/efeitos dos fármacos , Fibrose/genética , Regulação da Expressão Gênica/efeitos dos fármacos , Força da Mão , Camundongos , Camundongos Endogâmicos C57BL , Fibras Musculares Esqueléticas/efeitos dos fármacos , Fibras Musculares Esqueléticas/patologia , Nefrectomia , Hormônio Paratireóideo/sangue , RNA Mensageiro/biossíntese , Insuficiência Renal Crônica/sangue , Insuficiência Renal Crônica/tratamento farmacológico , Teste de Desempenho do Rota-Rod , Análise de Sequência de RNA , Termogênese/efeitos dos fármacos , Ganho de Peso/efeitos dos fármacos
6.
Biochim Biophys Acta Gen Subj ; 1864(10): 129676, 2020 10.
Artigo em Inglês | MEDLINE | ID: mdl-32649980

RESUMO

BACKGROUND: Oxidative stress is crucial player in skeletal muscle atrophy pathogenesis. S-allyl cysteine (SAC), an organosulfur compound of Allium sativum, possesses broad-spectrum properties including immuno- and redox-modulatory impact. Considering the role of SAC in regulating redox balance, we hypothesize that SAC may have a protective role in oxidative-stress induced atrophy. METHODS: C2C12 myotubes were treated with H2O2 (100 µM) in the presence or absence of SAC (200 µM) to study morphology, redox status, inflammatory cytokines and proteolytic systems using fluorescence microscopy, biochemical analysis, real-time PCR and immunoblotting approaches. The anti-atrophic potential of SAC was confirmed in denervation-induced atrophy model. RESULTS: SAC pre-incubation (4 h) could protect the myotube morphology (i.e. length/diameter/fusion index) from atrophic effects of H2O2. Lower levels of ROS, lipid peroxidation, oxidized glutathione and altered antioxidant enzymes were observed in H2O2-exposed cells upon pre-treatment with SAC. SAC supplementation also suppressed the rise in cytokines levels (TWEAK/IL6/myostatin) caused by H2O2. SAC treatment also moderated the degradation of muscle-specific proteins (MHCf) in the H2O2-treated myotubes supported by lower induction of diverse proteolytic systems (i.e. cathepsin, calpain, ubiquitin-proteasome E3-ligases, caspase-3, autophagy). Denervation-induced atrophy in mice illustrates that SAC administration alleviates the negative effects (i.e. mass loss, decreased cross-sectional area, up-regulation of proteolytic systems, and degradation of total/specific protein) of denervation on muscles. CONCLUSIONS: SAC exerts significant anti-atrophic effects to protect myotubes from H2O2-induced protein loss and myofibers from denervation-induced muscle loss, due to the prevention of elevated proteolytic systems and inflammatory/oxidative molecules. GENERAL SIGNIFICANCE: The results signify the potential of SAC against muscle atrophy.


Assuntos
Cisteína/análogos & derivados , Atrofia Muscular/tratamento farmacológico , Substâncias Protetoras/uso terapêutico , Animais , Linhagem Celular , Cisteína/farmacologia , Cisteína/uso terapêutico , Modelos Animais de Doenças , Peróxido de Hidrogênio/metabolismo , Camundongos , Fibras Musculares Esqueléticas/efeitos dos fármacos , Fibras Musculares Esqueléticas/metabolismo , Fibras Musculares Esqueléticas/patologia , Atrofia Muscular/metabolismo , Atrofia Muscular/patologia , Estresse Oxidativo/efeitos dos fármacos , Substâncias Protetoras/farmacologia
7.
J Med Chem ; 63(14): 7827-7839, 2020 07 23.
Artigo em Inglês | MEDLINE | ID: mdl-32657583

RESUMO

RNA repeat expansions are responsible for more than 30 incurable diseases. Among them is myotonic dystrophy type 1 (DM1), the most common form of adult on-set muscular dystrophy. DM1 is caused by an r(CUG) repeat expansion [r(CUG)exp] located in the 3' untranslated region (UTR) of the dystrophia myotonica protein kinase gene. This repeat expansion is highly structured, forming a periodic array of 5'CUG/3'GUC internal loop motifs. We therefore designed dimeric compounds that simultaneously bind two of these motifs by connecting two RNA-binding modules with peptoid linkers of different geometries and lengths. The optimal linker contains two proline residues and enhances compound affinity. Equipping this molecule with a bleomycin A5 cleaving module converts the simple binding compound into a potent allele-selective cleaver of r(CUG)exp. This study shows that the linker in modularly assembled ligands targeting RNA can be optimized to afford potent biological activity.


Assuntos
Benzimidazóis/farmacologia , Oligopeptídeos/farmacologia , RNA/química , Benzimidazóis/síntese química , Bleomicina/análogos & derivados , Bleomicina/síntese química , Bleomicina/farmacologia , Dano ao DNA/efeitos dos fármacos , Desenho de Fármacos , Humanos , Fibras Musculares Esqueléticas/efeitos dos fármacos , Oligopeptídeos/síntese química , RNA/efeitos dos fármacos , RNA/genética , Bibliotecas de Moléculas Pequenas/síntese química , Bibliotecas de Moléculas Pequenas/farmacologia , Sequências de Repetição em Tandem/efeitos dos fármacos
8.
J Anim Sci ; 98(7)2020 Jul 01.
Artigo em Inglês | MEDLINE | ID: mdl-32619223

RESUMO

A randomized complete block design experiment with 32 yearling crossbred steers (average body weight [BW] = 442 ± 17.0 kg) fed a steam-flaked corn-based diet was used to evaluate the effects of dietary Zn (KemTRACE Zn propionate 27; Kemin Industries, Inc., Des Moines, IA) supplementation on live growth performance, skeletal muscle fiber, and beta-adrenergic receptor (ß-AR) characteristics during the finishing phase. Steers were blocked by BW (n = 4 blocks; 8 steers/block), assigned to pens (n = 4 steers/pen), and randomly assigned to the following treatments: control (CON; 0.0 g/[head (hd) · d] of additional Zn) or additional dietary Zn (ZnP; 1.0 g/[hd · d] additional Zn). The basal diet contained Zn (60 ppm dry matter basis) from ZnSO4; additional Zn was top-dressed at feeding. Ractopamine hydrochloride (RH; Optaflexx: Elanco Animal Health, Greenfield, IN) was included at 300 mg/(hd · d) for the final 28 d of the 111-d feeding period. Longissimus muscle biopsy samples, BW, and blood were obtained on days 0, 42, 79, and 107. Final BW was collected prior to shipping on day 111. Biopsy samples were used for immunohistochemical (IHC), mRNA, and protein analysis. Serum urea nitrogen (SUN) and nonesterified fatty acid (NEFA) concentrations were measured. Steers fed ZnP had a greater average daily gain (P = 0.02) and gain to feed ratio (G:F; P = 0.03) during the RH feeding period compared with CON. There were no differences (P > 0.05) in other growth performance variables, carcass traits, mRNA abundance, or relative protein concentration for fiber type and ß-AR. Fiber types I and IIA had no differences in the cross-sectional area; however, the IIX area was greater for CON (P < 0.04) compared with ZnP and increased (P < 0.02) over time. There were no differences between treatments for the ß1-AR density (P > 0.05) in skeletal muscle tissue throughout the study. A treatment × day interaction was observed in ß2-AR density (P = 0.02) and ß3-AR density (P = 0.02) during the RH feeding period, where the abundance of the receptors increased with ZnP but did not change in CON. Compared with CON, ZnP had greater (P < 0.01) mean NEFA concentrations. Mean SUN concentrations did increase by day (P < 0.01). Additional dietary Zn, supplied as Zn propionate, upregulates ß2-AR and ß3-AR and improves growth performance in feedlot steers during the RH feeding period, likely through a shift of resource utilization from lipogenesis to muscle maintenance and hypertrophy.


Assuntos
Bovinos , Suplementos Nutricionais , Fibras Musculares Esqueléticas/efeitos dos fármacos , Propionatos/farmacologia , Ração Animal/análise , Animais , Nitrogênio da Ureia Sanguínea , Composição Corporal/efeitos dos fármacos , Peso Corporal/efeitos dos fármacos , Bovinos/crescimento & desenvolvimento , Bovinos/metabolismo , Dieta/veterinária , Fibras na Dieta/metabolismo , Masculino , Fibras Musculares Esqueléticas/fisiologia , Músculo Esquelético/efeitos dos fármacos , Músculo Esquelético/metabolismo , Fenetilaminas/administração & dosagem , Fenetilaminas/farmacologia , Propionatos/administração & dosagem
9.
PLoS One ; 15(7): e0236923, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32730329

RESUMO

Heart failure (HF) impairs diaphragm function. Animal models realistically mimicking HF should feature both the cardiac alterations and the diaphragmatic dysfunction characterizing this disease. The isoproterenol-induced HF model is widely used, but whether it presents diaphragmatic dysfunction is unknown. However, indirect data from research in other fields suggest that isoproterenol could increase diaphragm function. The aim of this study was to test the hypothesis that the widespread rodent model of isoproterenol-induced HF results in increased diaphragmatic contractility. Forty C57BL/6J male mice were randomized into 2 groups: HF and healthy controls. After 30 days of isoproterenol infusion to establish HF, in vivo diaphragmatic excursion and ex vivo isolated diaphragm contractibility were measured. As compared with healthy controls, mice with isoproterenol-induced HF showed the expected changes in structural and functional echocardiographic parameters and lung edema. isoproterenol-induced HF increased in vivo diaphragm excursion (by ≈30%, p<0.01) and increased by ≈50% both ex vivo peak specific force (p<0.05) and tetanic force (p<0.05) at almost all 10-100 Hz frequencies (p<0.05), with reduced fatigue resistance (p<0.01) when compared with healthy controls. Expression of myosin genes encoding the main muscle fiber types revealed that Myh4 was higher in isoproterenol-induced HF than in healthy controls (p<0.05), suggesting greater distribution of type IIb fibers. These results show that the conventional isoproterenol-induced HF model increases diaphragm contraction, a finding contrary to what is observed in patients with HF. Therefore, this specific model seems limited for translational an integrative HF research, especially when cardio-respiratory interactions are investigated.


Assuntos
Agonistas Adrenérgicos beta/toxicidade , Diafragma/fisiopatologia , Insuficiência Cardíaca/fisiopatologia , Isoproterenol/toxicidade , Fibras Musculares Esqueléticas/patologia , Proteínas Musculares/metabolismo , Edema Pulmonar/patologia , Animais , Diafragma/efeitos dos fármacos , Modelos Animais de Doenças , Insuficiência Cardíaca/induzido quimicamente , Humanos , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Fibras Musculares Esqueléticas/efeitos dos fármacos , Edema Pulmonar/induzido quimicamente
10.
J Nat Med ; 74(4): 741-749, 2020 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-32601830

RESUMO

Cancer cachexia is a complex and multifactorial syndrome that influences about 50-80% of cancer patients and may lead to 20% of cancer deaths and muscle atrophy is the key characteristic of the syndrome. Recent researches have shown that myostatin is a negative regulator in the growth and differentiation of skeletal muscle. Herein, C2C12 cancer cachexia model was established with C26 conditioned culture medium (CCM), then treated with magnolol to evaluate the pharmacological activity of magnolol in myotube atrophy. Our results demonstrated that magnolol inhibited the activity of myostatin promotor and the myostatin signaling pathway. In C2C12 cancer cachexia model, magnolol decreased myostatin expression, inhibited the phosphorylation of SMAD2/3 activated by C26 conditioned culture medium (CCM), and elevated the phosphorylation of FOXO3a lowered by CCM. Myosin heavy chain (MyHC), myogenin (MyoG), and myogenic differentiation (MyoD), as three common myotube markers in C2C12 myotube, were decreased by CCM, which could be effectively reversed by magnolol via activation of AKT/mTOR-regulated protein synthesis and inhibition of ubiquitin-mediated proteolysis. This study reveals that magnolol inhibits myotube atrophy induced by CCM by increasing protein synthesis and decreasing ubiquitin-mediated proteolysis, so that magnolol is a promising leading compound in treating muscle atrophy induced by cancer cachexia.


Assuntos
Anti-Inflamatórios não Esteroides/química , Produtos Biológicos/química , Compostos de Bifenilo/química , Caquexia/tratamento farmacológico , Lignanas/química , Fibras Musculares Esqueléticas/efeitos dos fármacos , Atrofia Muscular/tratamento farmacológico , Miostatina/metabolismo , Neoplasias/complicações , Animais , Linhagem Celular Tumoral , Humanos , Camundongos , Transfecção
11.
Biochem Pharmacol ; 180: 114145, 2020 10.
Artigo em Inglês | MEDLINE | ID: mdl-32653593

RESUMO

We previously found that 20(S)-ginsenoside Rg3 (S-Rg3) promotes myoblast differentiation via an unknown mechanism. Here we measured levels of myosin heavy chain (MHC) and myogenin, markers of myoblast differentiation, using Western blot analysis and immunofluorescence staining. Notably, S-Rg3 treatment of C2C12 myoblasts led to increased muscle differentiation and protection from muscle atrophy in a dexamethasone (DEX)-treated C2C12 myotube-based muscle atrophy model. This effect was likely caused by S-Rg3 treatment-induced promotion of Akt/mTOR phosphorylation and inhibition of FoxO3 nuclear transcription. Additionally, S-Rg3 treatment also led to increased fruit fly climbing distances (Drosophila melanogaster) and prevented muscle atrophy in aged fruit flies. Our study provides a mechanistic framework for understanding how S-Rg3 enhances myoblast differentiation and inhibits myotube atrophy through activation of the Akt/mTOR/FoxO3 signaling pathway, as demonstrated in vitro in C2C12 cells and in vivo in fruit flies.


Assuntos
Proteínas de Drosophila/metabolismo , Proteína Forkhead Box O3/metabolismo , Ginsenosídeos/farmacologia , Fibras Musculares Esqueléticas/metabolismo , Atrofia Muscular/metabolismo , Mioblastos/metabolismo , Proteínas Associadas à Matriz Nuclear/metabolismo , Proteínas Proto-Oncogênicas c-akt/metabolismo , Animais , Diferenciação Celular/efeitos dos fármacos , Diferenciação Celular/fisiologia , Linhagem Celular , Relação Dose-Resposta a Droga , Drosophila melanogaster , Camundongos , Fibras Musculares Esqueléticas/efeitos dos fármacos , Atrofia Muscular/patologia , Atrofia Muscular/prevenção & controle , Mioblastos/efeitos dos fármacos , Transdução de Sinais/efeitos dos fármacos , Transdução de Sinais/fisiologia
12.
PLoS Biol ; 18(6): e3000731, 2020 06.
Artigo em Inglês | MEDLINE | ID: mdl-32479501

RESUMO

The nuclear lamina protein lamin A/C is a key component of the nuclear envelope. Mutations in the lamin A/C gene (LMNA) are identified in patients with various types of laminopathy-containing diseases, which have features of accelerated aging and osteoporosis. However, the underlying mechanisms for laminopathy-associated osteoporosis remain largely unclear. Here, we provide evidence that loss of lamin A/C in skeletal muscles, but not osteoblast (OB)-lineage cells, results in not only muscle aging-like deficit but also trabecular bone loss, a feature of osteoporosis. The latter is due in large part to elevated bone resorption. Further cellular studies show an increase of osteoclast (OC) differentiation in cocultures of bone marrow macrophages/monocytes (BMMs) and OBs after treatment with the conditioned medium (CM) from lamin A/C-deficient muscle cells. Antibody array screening analysis of the CM proteins identifies interleukin (IL)-6, whose expression is markedly increased in lamin A/C-deficient muscles. Inhibition of IL-6 by its blocking antibody in BMM-OB cocultures diminishes the increase of osteoclastogenesis. Knockout (KO) of IL-6 in muscle lamin A/C-KO mice diminishes the deficits in trabecular bone mass but not muscle. Further mechanistic studies reveal an elevation of cellular senescence marked by senescence-associated beta-galactosidase (SA-ß-gal), p16Ink4a, and p53 in lamin A/C-deficient muscles and C2C12 muscle cells, and the p16Ink4a may induce senescence-associated secretory phenotype (SASP) and IL-6 expression. Taken together, these results suggest a critical role for skeletal muscle lamin A/C to prevent cellular senescence, IL-6 expression, hyperosteoclastogenesis, and trabecular bone loss, uncovering a pathological mechanism underlying the link between muscle aging/senescence and osteoporosis.


Assuntos
Envelhecimento/patologia , Lamina Tipo A/deficiência , Músculo Esquelético/patologia , Osteoporose/patologia , Animais , Anticorpos Bloqueadores/farmacologia , Fenômenos Biomecânicos , Reabsorção Óssea/complicações , Reabsorção Óssea/patologia , Osso Esponjoso/efeitos dos fármacos , Osso Esponjoso/patologia , Diferenciação Celular/efeitos dos fármacos , Senescência Celular/efeitos dos fármacos , Interleucina-6/metabolismo , Camundongos Knockout , Fibras Musculares Esqueléticas/efeitos dos fármacos , Fibras Musculares Esqueléticas/metabolismo , Músculo Esquelético/efeitos dos fármacos , Tamanho do Órgão/efeitos dos fármacos , Osteoclastos/efeitos dos fármacos , Osteoclastos/patologia , Osteogênese/efeitos dos fármacos , Osteoporose/sangue , Fenótipo
13.
Nat Commun ; 11(1): 2695, 2020 06 01.
Artigo em Inglês | MEDLINE | ID: mdl-32483258

RESUMO

Obesity and type 2 diabetes (T2D) are metabolic disorders influenced by lifestyle and genetic factors that are characterized by insulin resistance in skeletal muscle, a prominent site of glucose disposal. Numerous genetic variants have been associated with obesity and T2D, of which the majority are located in non-coding DNA regions. This suggests that most variants mediate their effect by altering the activity of gene-regulatory elements, including enhancers. Here, we map skeletal muscle genomic enhancer elements that are dynamically regulated after exposure to the free fatty acid palmitate or the inflammatory cytokine TNFα. By overlapping enhancer positions with the location of disease-associated genetic variants, and resolving long-range chromatin interactions between enhancers and gene promoters, we identify target genes involved in metabolic dysfunction in skeletal muscle. The majority of these genes also associate with altered whole-body metabolic phenotypes in the murine BXD genetic reference population. Thus, our combined genomic investigations identified genes that are involved in skeletal muscle metabolism.


Assuntos
Diabetes Mellitus Tipo 2/genética , Diabetes Mellitus Tipo 2/metabolismo , Elementos Facilitadores Genéticos , Resistência à Insulina/genética , Músculo Esquelético/metabolismo , Obesidade/genética , Obesidade/metabolismo , Animais , Linhagem Celular , Cromatina/genética , Cromatina/metabolismo , Diabetes Mellitus Tipo 2/patologia , Feminino , Perfilação da Expressão Gênica , Estudo de Associação Genômica Ampla , Humanos , Masculino , Camundongos , Fibras Musculares Esqueléticas/efeitos dos fármacos , Fibras Musculares Esqueléticas/metabolismo , Obesidade/patologia , Ácido Palmítico/farmacologia , Fatores de Iniciação de Peptídeos/genética , Polimorfismo de Nucleotídeo Único , Regiões Promotoras Genéticas , Fator de Necrose Tumoral alfa/farmacologia
14.
Am J Physiol Endocrinol Metab ; 319(2): E265-E275, 2020 08 01.
Artigo em Inglês | MEDLINE | ID: mdl-32459525

RESUMO

Saturated fatty acids (SFAs) are implicated in muscle inflammation/cell stress and insulin resistance, but the catalog of factors involved is incomplete. SFA derivatives that accumulate with mismatched FA availability and FA oxidation (FAO) are likely involved, and evidence has emerged that select acylcarnitines should be considered. To understand if excessive long-chain acylcarnitine accumulation and limited FAO associate with lipotoxicity, carnitine palmitoyltransferase 2 knockout C2C12 cells were generated (CPT2 KO). CPT2 KO was confirmed by Western blot, increased palmitoylcarnitine accumulation, and loss of FAO capacity. There was no effect of CPT2 KO on palmitic acid (PA) concentration-dependent increases in media IL-6 or adenylate kinase. PA at 200 and 500 µM did not trigger cell stress responses (phospho-Erk, -JNK, or -p38) above that of vehicle in WT or CPT2 KO cells. In contrast, loss of CPT2 exacerbated PA-induced insulin resistance (acute phospho-Akt; 10 or 100 nM insulin) by as much as ~50-96% compared with WT. Growing cells in carnitine-free media abolished differences between WT and CPT2 KO, but this did not fully rescue PA-induced insulin resistance. The results suggest that PA-induced insulin resistance stems in part from palmitoylcarnitine accumulation, further supporting the hypothesis that select acylcarnitines participate in cell signaling and, when in excess, can compromise cell function. Since carnitine-free conditions could not fully rescue insulin signaling, and CPT2 KO did not alter cell stress responses, the majority of PA-induced "lipotoxicity" in C2C12 myotubes cannot be attributed to palmitoylcarnitine alone.


Assuntos
Carnitina O-Palmitoiltransferase/genética , Carnitina O-Palmitoiltransferase/fisiologia , Técnicas de Inativação de Genes , Resistência à Insulina/fisiologia , Fibras Musculares Esqueléticas/fisiologia , Ácido Palmítico/farmacologia , Animais , Linhagem Celular , Camundongos , Fibras Musculares Esqueléticas/citologia , Fibras Musculares Esqueléticas/efeitos dos fármacos , Palmitoilcarnitina/metabolismo , Transdução de Sinais/fisiologia
15.
Am J Chin Med ; 48(3): 631-650, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32329640

RESUMO

The loss of skeletal muscle mass and function is a serious consequence of chronic diseases and aging. BST204 is a purified ginseng (the root of Panax ginseng) extract that has been processed using ginsenoside-ß-glucosidase and acid hydrolysis to enrich ginsenosides Rg3 and Rh2 from the crude ginseng. BST204 has a broad range of health benefits, but its effects and mechanism on muscle atrophy are currently unknown. In this study, we have examined the effects and underlying mechanisms of BST204 on myotube formation and myotube atrophy induced by tumor necrosis factor-α (TNF-α). BST204 promotes myogenic differentiation and multinucleated myotube formation through Akt activation. BST204 prevents myotube atrophy induced by TNF-α through the activation of Akt/mTOR signaling and down-regulation of muscle-specific ubiquitin ligases, MuRF1, and Atrogin-1. Furthermore, BST204 treatment in atrophic myotubes suppresses mitochondrial reactive oxygen species (ROS) production and regulates mitochondrial transcription factors such as NRF1 and Tfam, through enhancing the activity and expression of peroxisome proliferator-activated receptor-γ coactivator1α (PGC1α). Collectively, our findings indicate that BST204 improves myotube formation and PGC1α-mediated mitochondrial function, suggesting that BST204 is a potential therapeutic or neutraceutical remedy to intervene muscle weakness and atrophy.


Assuntos
Desenvolvimento Muscular/efeitos dos fármacos , Fibras Musculares Esqueléticas/efeitos dos fármacos , Panax/química , Fitoterapia , Extratos Vegetais/farmacologia , Extratos Vegetais/uso terapêutico , Animais , Atrofia/induzido quimicamente , Atrofia/tratamento farmacológico , Humanos , Mitocôndrias Musculares/metabolismo , Fibras Musculares Esqueléticas/metabolismo , Fibras Musculares Esqueléticas/patologia , Fibras Musculares Esqueléticas/fisiologia , Fator 1 Nuclear Respiratório/metabolismo , Coativador 1-alfa do Receptor gama Ativado por Proliferador de Peroxissomo/metabolismo , Extratos Vegetais/isolamento & purificação , Proteínas Proto-Oncogênicas c-akt/metabolismo , Espécies Reativas de Oxigênio/metabolismo , Transdução de Sinais/efeitos dos fármacos , Estimulação Química , Serina-Treonina Quinases TOR/metabolismo , Fator de Necrose Tumoral alfa
16.
Artigo em Inglês | MEDLINE | ID: mdl-32305458

RESUMO

Proprioception in mammals and invertebrates occurs through stretch activated ion channels (SACs) localized in sensory endings. In mammals, the primary organs for proprioception are the intrafusal muscle spindles embedded within extrafusal muscle. In invertebrates there are varied types of sensory organs, from chordotonal organs spanning joints to muscle receptor organs (MRO) which are analogous to the mammalian muscle spindles that monitor stretch of muscle fibers. A subset of SACs are the PIEZO channels. They are comprised of a distinct type of protein sequence and are similar among species, from mammals to invertebrates. We screened several new agents (YODA 1, JEDI 2, OB 1 and DOOKU) which have been identified to act on SACs of the PIEZO 1 subtype. JEDI 2 increased activity in the crayfish MRO but not the crab chordotonal organs. The SACs of the crustacean proprioceptors have not been satisfactorily pharmacologically classified, nor has their molecular makeup been identified. We screened these pharmacological agents on model sensory organs in crustaceans to learn more about their subtype classification and compare genomic profiles of related species.


Assuntos
Astacoidea/fisiologia , Braquiúros/fisiologia , Canais Iônicos/efeitos dos fármacos , Propriocepção , Animais , Feminino , Fibras Musculares Esqueléticas/citologia , Fibras Musculares Esqueléticas/efeitos dos fármacos , Fusos Musculares/citologia , Fusos Musculares/efeitos dos fármacos , Células Receptoras Sensoriais/citologia , Células Receptoras Sensoriais/efeitos dos fármacos
17.
Sci Rep ; 10(1): 6065, 2020 04 08.
Artigo em Inglês | MEDLINE | ID: mdl-32269254

RESUMO

Blood ammonia increases during exercise, and it has been suggested that this increase is both a central and peripheral fatigue factor. Although green tea catechins (GTCs) are known to improve exercise endurance by enhancing lipid metabolism in skeletal muscle, little is known about the relationship between ammonia metabolism and the endurance-improving effect of GTCs. Here, we examined how ammonia affects endurance capacity and how GTCs affect ammonia metabolism in vivo in mice and how GTCs affect mouse skeletal muscle and liver in vitro. In mice, blood ammonia concentration was significantly negatively correlated with exercise endurance capacity, and hyperammonaemia was found to decrease whole-body fat expenditure and fatty acid oxidation-related gene expression in skeletal muscle. Repeated ingestion of GTCs combined with regular exercise training improved endurance capacity and the expression of urea cycle-related genes in liver. In C2C12 myotubes, hyperammonaemia suppressed mitochondrial respiration; however, pre-incubation with GTCs rescued this suppression. Together, our results demonstrate that hyperammonaemia decreases both mitochondrial respiration in myotubes and whole-body aerobic metabolism. Thus, GTC-mediated increases in ammonia metabolism in liver and resistance to ammonia-induced suppression of mitochondrial respiration in skeletal muscle may underlie the endurance-improving effect of GTCs.


Assuntos
Amônia/sangue , Catequina/farmacologia , Condicionamento Físico Animal/métodos , Esforço Físico , Chá/química , Animais , Catequina/administração & dosagem , Linhagem Celular , Respiração Celular , Ácidos Graxos/metabolismo , Fígado/efeitos dos fármacos , Fígado/metabolismo , Masculino , Camundongos , Camundongos Endogâmicos BALB C , Fibras Musculares Esqueléticas/efeitos dos fármacos , Fibras Musculares Esqueléticas/metabolismo , Ureia/metabolismo
18.
Nutrients ; 12(3)2020 Feb 28.
Artigo em Inglês | MEDLINE | ID: mdl-32121211

RESUMO

This study aimed to investigate the long-term effects of training intervention and resting on protein expression and stability of peroxisome proliferator-activated receptor ß/δ (PPARß), peroxisome proliferator-activated receptor gamma coactivator 1-α (PGC1α), glucose transporter type 4 (GLUT4), and mitochondrial proteins, and determine whether glucose homeostasis can be regulated through stable expression of these proteins after training. Rats swam daily for 3, 6, 9, 14, or 28 days, and then allowed to rest for 5 days post-training. Protein and mRNA levels were measured in the skeletal muscles of these rats. PPARß was overexpressed and knocked down in myotubes in the skeletal muscle to investigate the effects of swimming training on various signaling cascades of PGC-1α transcription, insulin signaling, and glucose uptake. Exercise training (Ext) upregulated PPARß, PGC-1α, GLUT4, and mitochondrial enzymes, including NADH-ubiquinone oxidoreductase (NUO), cytochrome c oxidase subunit I (COX1), citrate synthase (CS), and cytochrome c (Cyto C) in a time-dependent manner and promoted the protein stability of PPARß, PGC-1α, GLUT4, NUO, CS, and Cyto C, such that they were significantly upregulated 5 days after training cessation. PPARß overexpression increased the PGC-1α protein levels post-translation and improved insulin-induced signaling responsiveness and glucose uptake. The present results indicate that Ext promotes the protein stability of key mitochondria enzymes GLUT4, PGC-1α, and PPARß even after Ext cessation.


Assuntos
Glucose/metabolismo , Insulina/farmacologia , Músculo Esquelético/metabolismo , PPAR beta/metabolismo , Coativador 1-alfa do Receptor gama Ativado por Proliferador de Peroxissomo/metabolismo , Condicionamento Físico Animal , Animais , Transportador de Glucose Tipo 4/metabolismo , Meia-Vida , Masculino , Camundongos , Mitocôndrias/efeitos dos fármacos , Mitocôndrias/enzimologia , Proteínas Mitocondriais/metabolismo , Fibras Musculares Esqueléticas/efeitos dos fármacos , Fibras Musculares Esqueléticas/metabolismo , Músculo Esquelético/efeitos dos fármacos , PPAR beta/genética , Coativador 1-alfa do Receptor gama Ativado por Proliferador de Peroxissomo/genética , Biossíntese de Proteínas/efeitos dos fármacos , Estabilidade Proteica/efeitos dos fármacos , Ratos Wistar , Transcrição Genética/efeitos dos fármacos , Regulação para Cima/efeitos dos fármacos
19.
J Endocrinol ; 245(2): 259-279, 2020 05.
Artigo em Inglês | MEDLINE | ID: mdl-32134722

RESUMO

Lifestyle modifications, including physical exercise (PhyEx), are well-known treatments for metabolic syndrome (MetS), a cluster of metabolic and cardiovascular risk factors often associated to hypogonadism. Given the trophic role of testosterone on skeletal muscle (SkM), this study was aimed at evaluating the effects of testosterone treatment on SkM metabolism and exercise performance in male rabbits with high-fat diet (HFD)-induced MetS. HFD rabbits, treated or not with testosterone (30 mg/kg/week) for 12 weeks, were compared to regular diet animals (RD). A subset of each group was exercise-trained for 12 weeks. HFD increased type-II (fast, glycolytic) and decreased type-I (slow, oxidative) muscle fibers compared to RD as evaluated by RT-PCR and histochemistry. Testosterone reverted these effects, also inducing the expression of mitochondrial respiration enzymes and normalizing HFD-induced mitochondrial cristae reduction. Moreover, testosterone significantly increased the expression of myogenic/differentiation markers and genes related to glucidic/lipid metabolism. At the end of the PhyEx protocol, when compared to RD, HFD rabbits showed a significant reduction of running distance and running time, while testosterone counteracted this effect, also decreasing lactate production. In the trained groups, muscle histology showed a significant reduction of oxidative fibers in HFD compared to RD and the positive effect of testosterone in maintaining oxidative metabolism, as also demonstrated by analyzing mitochondrial ultrastructure, succinate dehydrogenase activity and ATP production. Our results indicate that testosterone could be useful to promote oxidative muscle metabolism altered by MetS, thus improving exercise performance. Conversely, testosterone administration to otherwise eugonadal rabbits (RD) only increased muscle fiber diameter but not endurance performance.


Assuntos
Síndrome Metabólica/fisiopatologia , Fibras Musculares Esqueléticas/efeitos dos fármacos , Músculo Esquelético/efeitos dos fármacos , Resistência Física/efeitos dos fármacos , Testosterona/farmacologia , Animais , Dieta Hiperlipídica , Modelos Animais de Doenças , Masculino , Síndrome Metabólica/etiologia , Condicionamento Físico Animal , Coelhos
20.
Phytomedicine ; 68: 153178, 2020 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-32126492

RESUMO

BACKGROUND: Lowering blood glucose levels by increasing glucose uptake in insulin target tissues, such as skeletal muscle and adipose tissue, is one strategy to discover and develop antidiabetic drugs from natural products used as traditional medicines. PURPOSE: Our goal was to reveal the mechanism and activity of acacetin (5,7-dihydroxy-4'-methoxyflavone), one of the major compounds in Agastache rugose, in stimulating glucose uptake in muscle cells. METHODS: To determine whether acacetin promotes GLUT4-dependent glucose uptake in cultured L6 skeletal muscle cells, we performed a [14C] 2-deoxy-D-glucose (2-DG) uptake assay after treating differentiated L6-GLUT4myc cells with acacetin. RESULTS: Acacetin dose-dependently increased 2-DG uptake by enhancing GLUT4 translocation to the plasma membrane. Our results revealed that acacetin activated the CaMKII-AMPK pathway by increasing intracellular calcium concentrations. We also found that aPKCλ/ζ phosphorylation and intracellular reactive oxygen species (ROS) production were involved in acacetin-induced GLUT4 translocation. Moreover, acacetin-activated AMPK inhibited intracellular lipid accumulation and increased 2-DG uptake in HepG2 cells. CONCLUSION: Taken together, these results suggest that acacetin might be useful as an antidiabetic functional ingredient. Subsequent experiments using disease model animals are needed to verify our results.


Assuntos
Proteínas de Ligação a DNA/metabolismo , Flavonas/farmacologia , Glucose/metabolismo , Insulina/metabolismo , Fibras Musculares Esqueléticas/efeitos dos fármacos , Fatores de Transcrição/metabolismo , Animais , Membrana Celular/efeitos dos fármacos , Membrana Celular/metabolismo , Células Cultivadas , Desoxiglucose/farmacocinética , Relação Dose-Resposta a Droga , Glucose/farmacocinética , Transportador de Glucose Tipo 4/metabolismo , Células Hep G2 , Humanos , Hipoglicemiantes/farmacologia , Fibras Musculares Esqueléticas/metabolismo , Fosforilação , Transporte Proteico/efeitos dos fármacos , Espécies Reativas de Oxigênio/metabolismo
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA