RESUMO
Interleukin-6 (IL-6) is a pro-inflammatory cytokine associated with skeletal muscle wasting in cancer cachexia. The control of gene expression by microRNAs (miRNAs) in muscle wasting involves the regulation of thousands of target transcripts. However, the miRNA-target networks associated with IL6-induced muscle atrophy remain to be characterized. Here, we show that IL-6 promotes the atrophy of C2C12 myotubes and changes the expression of 20 miRNAs (5 up-regulated and 15 down-regulated). Gene Ontology analysis of predicted miRNAs targets revealed post-transcriptional regulation of genes involved in cell differentiation, apoptosis, migration, and catabolic processes. Next, we performed a meta-analysis of miRNA-published data that identified miR-497-5p, a down-regulated miRNAs induced by IL-6, also down-regulated in other muscle-wasting conditions. We used miR-497-5p mimics and inhibitors to explore the function of miR-497-5p in C2C12 myoblasts and myotubes. We found that miR-497-5p can regulate the expression of the cell cycle genes CcnD2 and CcnE1 without affecting the rate of myoblast cellular proliferation. Notably, miR-497-5p mimics induced myotube atrophy and reduced Insr expression. Treatment with miR-497-5p inhibitors did not change the diameter of the myotubes but increased the expression of its target genes Insr and Igf1r. These genes are known to regulate skeletal muscle regeneration and hypertrophy via insulin-like growth factor pathway and were up-regulated in cachectic muscle samples. Our miRNA-regulated network analysis revealed a potential role for miR-497-5p during IL6-induced muscle cell atrophy and suggests that miR-497-5p is likely involved in a compensatory mechanism of muscle atrophy in response to IL-6.
Assuntos
Interleucina-6/efeitos adversos , MicroRNAs/metabolismo , Células Musculares/metabolismo , Atrofia Muscular/genética , Animais , Caquexia/etiologia , Linhagem Celular , Proliferação de Células/efeitos dos fármacos , Proliferação de Células/genética , Regulação da Expressão Gênica/efeitos dos fármacos , Insulina/metabolismo , Camundongos , MicroRNAs/genética , Modelos Biológicos , Células Musculares/efeitos dos fármacos , Fibras Musculares Esqueléticas/efeitos dos fármacos , Fibras Musculares Esqueléticas/metabolismo , Fibras Musculares Esqueléticas/patologia , Atrofia Muscular/patologia , Neoplasias/complicações , Receptor IGF Tipo 1/genética , Receptor IGF Tipo 1/metabolismo , Receptor de Insulina/genética , Receptor de Insulina/metabolismo , Reprodutibilidade dos Testes , Transdução de Sinais/efeitos dos fármacosRESUMO
Obesity has a strong relationship to insulin resistance and diabetes mellitus, a chronic metabolic disease that alters many physiological functions. Naturally derived drugs have aroused great interest in treating obesity, and triterpenoids are natural compounds with multiple biological activities and antidiabetic mechanisms. Here, we evaluated the bioactivity of ursolic acid lactone (UAL), a lesser-known triterpenoid, obtained from Eucalyptus tereticornis. We used different cell lines to show for the first time that this molecule exhibits anti-inflammatory properties in a macrophage model, increases glucose uptake in insulin-resistant muscle cells, and reduces triglyceride content in hepatocytes and adipocytes. In 3T3-L1 adipocytes, UAL inhibited the expression of genes involved in adipogenesis and lipogenesis, enhanced the expression of genes involved in fat oxidation, and increased AMP-activated protein kinase phosphorylation. The range of biological activities demonstrated in vitro indicates that UAL is a promising molecule for fighting diabetes.
Assuntos
Eucalyptus/química , Lactonas/química , Lactonas/farmacologia , Triterpenos/química , Células 3T3-L1 , Adipócitos/efeitos dos fármacos , Adipócitos/metabolismo , Animais , Hepatócitos/efeitos dos fármacos , Hepatócitos/metabolismo , Macrófagos , Camundongos , Células Musculares/efeitos dos fármacos , Fosforilação/efeitos dos fármacos , Triglicerídeos/metabolismo , Triterpenos/farmacologia , Ácido UrsólicoRESUMO
OBJETIVE: Uremic sarcopenia is a complication of chronic kidney disease, particularly in its later stages, which leads to musculoskeletal disability. Uremic toxins have been linked to the pathogenesis of several manifestations of uremic syndrome. We sought to investigate whether indoxyl sulphate (IS), a protein-bound uremic toxin, is implicated in the development of uremic sarcopenia. MATERIAL AND METHODS: Myoblasts were exposed to IS at normal (0.6 mg/L, IS0.6), uremic (53 mg/L, IS53) or maximum uremic (236 mg/L, IS236) concentrations for 24, 48 and 72 h. Cell viability was evaluated by MTT assay and by 7-aminoactinomycin D staining. ROS generation and apoptosis were evaluated by flow cytometry. MyoD and myogenin mRNA expression was evaluated by qRT-PCR and myosin heavy chain expression by immunocytochemistry. RESULTS: Myoblast viability was reduced by IS236 in a time-dependent pattern (p <0.05; 84.4, 68.0, and 63.6%). ROS production was significantly higher (p <0.05) in cells exposed to IS53 and IS236 compared to control (untreated cells). The apoptosis rate was significantly higher in cells treated with IS53 and IS236 than in control after 48h (p <0.05; 4.7 ± 0.1% and 4.6 ± 0.3% vs. 3.1 ± 0.1%, respectively) and 72h (p <0.05; 9.6 ± 1.1% and 10.4 ± 0.3% vs. 3.1 ± 0.7%, respectively). No effect was observed on MyoD, myogenin, myosin heavy chain expression, and markers of myoblast differentiation at any IS concentration tested or time-point experiment. CONCLUSIONS: These data indicate that IS has direct toxic effects on myoblast by decreasing its viability and increasing cell apoptosis. IS may be a potential target for treating uremic sarcopenia.
Assuntos
Apoptose/efeitos dos fármacos , Indicã/farmacologia , Mioblastos/efeitos dos fármacos , Sarcopenia/induzido quimicamente , Uremia/induzido quimicamente , Animais , Morte Celular/efeitos dos fármacos , Diferenciação Celular/efeitos dos fármacos , Células Cultivadas , Camundongos , Células Musculares/efeitos dos fármacos , Células Musculares/fisiologia , Mioblastos/fisiologia , Espécies Reativas de Oxigênio/metabolismo , Sarcopenia/complicações , Toxinas Biológicas/metabolismo , Toxinas Biológicas/farmacologia , Regulação para Cima/efeitos dos fármacos , Uremia/complicaçõesRESUMO
Snakebites caused by the genus Bothrops are often associated with severe and complex local manifestations such as edema, pain, hemorrhage, and myonecrosis. Conventional treatment minimizes the systemic effects of venom; however, their local action is not neutralized. The purpose of this study was to evaluate the effect of photobiomodulation (PBM) on C2C12 muscle cells exposed to B. jararaca, B. jararacussu, and B. moojeni venoms on events involved in cell death and the release of inflammatory mediators. Cells were exposed to venoms and immediately irradiated with low-level laser (LLL) application in continuous wave at the wavelength of 660 nm, energy density of 4.4 J/cm2, power of 10 mW, area of 0.045 cm2, and time of 20 s. Cell integrity was analyzed by phase contrast microscope and cell death was performed by flow cytometry. In addition, interleukin IL1-ß, IL-6, and IL-10 levels were measured in the supernatant. Our results showed that the application of PBM increases cell viability and decreases cell death by apoptosis and necrosis. Moreover, the release of pro-inflammatory interleukins was also reduced. The data reported here indicate that PBM resulted in cytoprotection on myoblast C2C12 cells after venom exposure. This protection involves the modulation of cell death mechanism and decreased pro-inflammatory cytokine release.
Assuntos
Apoptose/efeitos dos fármacos , Bothrops/metabolismo , Venenos de Crotalídeos/toxicidade , Citocinas/biossíntese , Terapia com Luz de Baixa Intensidade , Células Musculares/patologia , Animais , Linhagem Celular , Forma Celular/efeitos dos fármacos , Camundongos , Células Musculares/efeitos dos fármacos , Células Musculares/efeitos da radiaçãoRESUMO
The anthelmintic treatment of nematode infections remains the pillar of worm control in both human and veterinary medicine. Since control is threatened by the appearance of drug resistant nematodes, there is a need to develop novel compounds, among which phytochemicals constitute potential anthelmintic agents. Caenorhabditis elegans has been pivotal in anthelmintic drug discovery and in revealing mechanisms of drug action and resistance. By using C. elegans, we here revealed the anthelmintic actions of three plant terpenoids -thymol, carvacrol and eugenol- at the behavioral level. Terpenoids produce a rapid paralysis of worms with a potency rank order carvacrol > thymol > eugenol. In addition to their paralyzing activity, they also inhibit egg hatching, which would, in turn, lead to a broader anthelmintic spectrum of activity. To identify drug targets, we performed an in vivo screening of selected strains carrying mutations in receptors involved in worm locomotion for determining resistance to the paralyzing effect of terpenoids. The assays revealed that two Cys-loop receptors with key roles in worm locomotion -Levamisole sensitive nicotinic receptor (L-AChR) and GABA(A) (UNC-49) receptor- are involved in the paralyzing effects of terpenoids. To decipher the mechanism by which terpenoids affect these receptors, we performed electrophysiological studies using a primary culture of C. elegans L1 muscle cells. Whole cell recordings from L1 cells demonstrated that terpenoids decrease macroscopic responses of L-AChR and UNC-49 receptor to their endogenous agonists, thus acting as inhibitors. Single-channel recordings from L-AChR revealed that terpenoids decrease the frequency of opening events, probably by acting as negative allosteric modulators. The fact that terpenoids act at different receptors may have important advantages regarding efficacy and development of resistance. Thus, our findings give support to the use of terpenoids as either an alternative or a complementary anthelmintic strategy to overcome the ever-increasing resistance of parasites to classical anthelmintic drugs.
Assuntos
Anti-Helmínticos/farmacologia , Caenorhabditis elegans/efeitos dos fármacos , Caenorhabditis elegans/enzimologia , Receptores de Canais Iônicos de Abertura Ativada por Ligante com Alça de Cisteína/antagonistas & inibidores , Terpenos/farmacologia , Animais , Células Cultivadas , Locomoção/efeitos dos fármacos , Células Musculares/efeitos dos fármacosRESUMO
Glucocorticoids (GCs) are potent anti-allergic compounds that function, at least in part, by inhibiting signaling pathways in mast cells. We hypothesized that the GC-induced mastocytopenia and suppression of mast cell activation are mediated by the advanced glycation end products (AGEs)/receptors of AGEs (RAGEs) signaling axis. We evaluated the role of AGEs in GC-mediated mastocytopenia and impaired mast cell degranulation in male Wistar rats and Swiss-Webster mice subcutaneously injected with dexamethasone or prednisolone (0.1 mg/kg) once a day for 21 consecutive days. The animals were treated with either the AGE inhibitor aminoguanidine (250 mg/kg), the RAGE antagonist FPS-ZM1 (1 mg/kg) or the galectin-3 antagonist GSC-100 (1 mg/kg) daily for 18 days, starting 3 days following GC treatment. Aminoguanidine inhibited GC-induced mast cell apoptosis and restored mast cell numbers in the pleural cavity of GC-treated rats. Aminoguanidine also reversed the GC-induced reduction in histamine release triggered by allergens or compound 48/80 in vitro. GC treatment induced RAGE and galectin expression in mast cells, and blocking these agents by FPS-ZM1 or GSC-100 significantly reversed mast cell numbers in the peritoneal cavity and mesenteric tissue of GC-treated mice. In addition, the combination of GC and AGE-induced mast cell apoptosis in vitro was inhibited by both FPS-ZM1 and GSC-100. We concluded that the GC-induced mastocytopenia and suppression of mast cell stimulation are associated with the gene transactivation of RAGE and galectin-3.
Assuntos
Glucocorticoides/farmacologia , Mastócitos/metabolismo , Receptor para Produtos Finais de Glicação Avançada/genética , Ativação Transcricional/genética , Animais , Apoptose/efeitos dos fármacos , Atrofia , Contagem de Células , Linhagem Celular , Dexametasona/farmacologia , Galectina 3/metabolismo , Produtos Finais de Glicação Avançada/metabolismo , Guanidinas/farmacologia , Linfopenia/patologia , Masculino , Mastócitos/efeitos dos fármacos , Camundongos , Células Musculares/efeitos dos fármacos , Células Musculares/metabolismo , Músculo Esquelético/patologia , Óxido Nítrico Sintase/antagonistas & inibidores , Óxido Nítrico Sintase/metabolismo , Ratos Wistar , Receptor para Produtos Finais de Glicação Avançada/metabolismo , Albumina Sérica/metabolismo , Ativação Transcricional/efeitos dos fármacos , Redução de Peso , Albumina Sérica GlicadaRESUMO
Mifepristone is the only FDA-approved drug for glycaemia control in patients with Cushing's syndrome and type 2 diabetes. Mifepristone also has beneficial effects in animal models of diabetes and patients with antipsychotic treatment-induced obesity. However, the mechanisms through which Mifepristone produces its beneficial effects are not completely elucidated. PURPOSE: To determine the effects of mifepristone on insulin-stimulated glucose uptake on a model of L6 rat-derived skeletal muscle cells. RESULTS: Mifepristone enhanced insulin-dependent glucose uptake, GLUT4 translocation to the plasma membrane and Akt Ser473 phosphorylation in L6 myotubes. In addition, mifepristone reduced oxygen consumption and ATP levels and increased AMPK Thr172 phosphorylation. The knockdown of AMPK prevented the effects of mifepristone on insulin response. CONCLUSIONS: Mifepristone enhanced insulin-stimulated glucose uptake through a mechanism that involves a decrease in mitochondrial function and AMPK activation in skeletal muscle cells.
Assuntos
Glucose/metabolismo , Insulina/farmacologia , Mifepristona/farmacologia , Células Musculares/metabolismo , Músculo Esquelético/citologia , Proteínas Proto-Oncogênicas c-akt/metabolismo , Adenilato Quinase/metabolismo , Animais , Mitocôndrias/efeitos dos fármacos , Mitocôndrias/metabolismo , Modelos Biológicos , Células Musculares/efeitos dos fármacos , Fosforilação/efeitos dos fármacos , RatosRESUMO
Testosterone (TES), other androgens and female sex steroids induce non-genomic rapid relaxing effects in airway smooth muscle (ASM). In guinea pig ASM, basal tension was relaxed by dehydroepiandrosterone (DHEA) and TES; 17ß-estradiol (E2) had a small effect. Blockers of L-type voltage dependent Ca2+ channel (L-VDCC, D-600) and store operated Ca2+ channel (SOC, 2-APB) also relaxed the basal tone. In tracheal myocytes, DHEA and TES diminished intracellular basal Ca2+ concentrations (b[Ca2+]i) as D-600+2-APB but to a higher extend. TES after D-600+2APB or Pyr3, a blocker of canonical transient receptor potential 3 (TRPC3), further decreased b[Ca2+]i rendering this response equal to TES alone. With indomethacin, the b[Ca2+]i decrease induced by the blockade of L-VDCC and TRPC3 was not changed by the addition of TES. PGE2 or forskolin addition after D600+2-APB, decreased b[Ca2+]i resembling TES response. An adenylate cyclase inhibitor followed by D-600+2-APB lowered b[Ca2+]i, TES showed no further effect. Carbachol-induced [Ca2+]i increment was reduced by TES or DHEA. 17ß-estradiol diminished KCl-induced contraction and, in tracheal myocytes, the voltage-dependent inward Ca2+ current. CONCLUSION: DHEA and TES diminish ASM tone and b[Ca2+]i by blocking L-VDCC and probably a constitutively active TRPC3, and by PGE2 synthesis. E2 lowers ASM basal tone by blocking only L-VDCC.
Assuntos
Canais de Cálcio Tipo L/metabolismo , Cálcio/metabolismo , Hormônios Esteroides Gonadais/farmacologia , Espaço Intracelular/metabolismo , Músculo Liso/fisiologia , Traqueia/fisiologia , Animais , Compostos de Boro/farmacologia , Carbacol/farmacologia , AMP Cíclico/metabolismo , Desidroepiandrosterona/farmacologia , Estradiol/farmacologia , Galopamil/farmacologia , Cobaias , Masculino , Células Musculares/efeitos dos fármacos , Células Musculares/metabolismo , Músculo Liso/efeitos dos fármacos , Prostaglandinas/metabolismo , Canais de Cátion TRPC/metabolismo , Testosterona/farmacologiaRESUMO
Tumor necrosis factor alpha (TNF-α) is a potent proinflammatory cytokine that plays a significant role in the pathogenesis of asthma by inducing hyperresponsiveness and airway remodeling. TNF-α diminishes the L-type voltage dependent Ca(2+) channel (L-VDCC) current in cardiac myocytes, an observation that seems paradoxical. In guinea pig sensitized tracheas KCl responses were lower than in control tissues. Serum from sensitized animals (Ser-S) induced the same phenomenon. In tracheal myocytes from nonsensitized (NS) and sensitized (S) guinea pigs, an L-VDCC current (ICa) was observed and diminished by Ser-S. The same decrease was detected in NS myocytes incubated with TNF-α, pointing out that this cytokine might be present in Ser-S. We observed that a small-molecule inhibitor of TNF-α (SMI-TNF) and a TNF-α receptor 1 (TNFR1) antagonist (WP9QY) reversed ICa decrease induced by Ser-S in NS myocytes, confirming the former hypothesis. U0126 (a blocker of ERK 1/2 kinase) also reverted the decrease in ICa. Neither cycloheximide (a protein synthesis inhibitor) nor actinomycin D (a transcription inhibitor) showed any effect on the TNF-α-induced ICa reduction. We found that CaV1.2 and CaV1.3 mRNA and proteins were expressed in tracheal myocytes and that sensitization did not modify them. In cardiac myocytes, ERK 1/2 phosphorylates two sites of the L-VDCC, augmenting or decreasing ICa; we postulate that, in guinea pig tracheal smooth muscle, TNF-α diminishes ICa probably by phosphorylating the L-VDCC site that reduces its activity through the ERK1/2 MAP kinase pathway.
Assuntos
Canais de Cálcio Tipo L/metabolismo , Sistema de Sinalização das MAP Quinases/efeitos dos fármacos , Músculo Liso/efeitos dos fármacos , Músculo Liso/metabolismo , Fator de Necrose Tumoral alfa/farmacologia , Animais , Butadienos/farmacologia , Células Cultivadas , Cicloeximida/farmacologia , Dactinomicina/farmacologia , Cobaias , Células Musculares/efeitos dos fármacos , Células Musculares/metabolismo , Nitrilas/farmacologia , Peptídeos Cíclicos/farmacologia , Traqueia/citologia , Fator de Necrose Tumoral alfa/antagonistas & inibidoresRESUMO
Flavonoid galetin 3,6-dimethyl ether (FGAL) has been isolated from the aerial parts of Piptadenia stipulaceae and has shown a spasmolytic effect in guinea pig ileum. Thus, we aimed to characterize its relaxant mechanism of action. FGAL exhibited a higher relaxant effect on ileum pre-contracted by histamine (EC50=1.9±0.4×10(-7) M) than by KCl (EC50=2.6±0.5×10(-6) M) or carbachol (EC50=1.8±0.4×10(-6) M). The flavonoid inhibited the cumulative contractions to histamine, as well as to CaCl2 in depolarizing medium nominally Ca(2+)-free. The flavonoid relaxed the ileum pre-contracted by S-(-)-Bay K8644 (EC50=9.5±1.9×10(-6) M) but less potently pre-contracted by KCl or histamine. CsCl attenuated the relaxant effect of FGAL (EC50=1.1±0.3×10(-6) M), but apamin or tetraethylammonium (1mM) had no effect (EC50=2.6±0.2×10(-7) and 1.6±0.3×10(-7) M, respectively), ruling out the involvement of small and big conductance Ca(2+)-activated K(+) channels (SKCa and BKCa, respectively). Either 4-aminopyridine or glibenclamide attenuated the relaxant effect of FGAL (EC50=1.8±0.2×10(-6) and 1.5±0.5×10(-6) M, respectively), indicating the involvement of voltage- and ATP-sensitive K(+) channels (KV and KATP, respectively). FGAL did not alter the viability of intestinal myocytes in the MTT assay and decreased (88%) Fluo-4 fluorescence, indicating a decrease in cytosolic Ca(2+) concentration. Therefore, the relaxant mechanism of FGAL involves pseudo-irreversible noncompetitive antagonism of histaminergic receptors, KV and KATP activation and blockade of CaV1, thus leading to a reduction in cytosolic Ca(2+) levels.