RESUMEN
Previous studies have shown that vitamin C (VC), an essential vitamin for the human body, can promote the differentiation of muscle satellite cells (MuSCs) in vitro and play an important role in skeletal muscle post-injury regeneration. However, the molecular mechanism of VC regulating MuSC proliferation has not been elucidated. In this study, the role of VC in promoting MuSC proliferation and its molecular mechanism were explored using cell molecular biology and animal experiments. The results showed that VC accelerates the progress of skeletal muscle post-injury regeneration by promoting MuSC proliferation in vivo. VC can also promote skeletal muscle regeneration in the case of atrophy. Using the C2C12 myoblast murine cell line, we observed that VC also stimulated cell proliferation. In addition, after an in vitro study establishing the occurrence of a physical interaction between VC and Pax7, we observed that VC also upregulated the total and nuclear Pax7 protein levels. This mechanism increased the expression of Myf5 (Myogenic Factor 5), a Pax7 target gene. This study establishes a theoretical foundation for understanding the regulatory mechanisms underlying VC-mediated MuSC proliferation and skeletal muscle regeneration. Moreover, it develops the application of VC in animal muscle nutritional supplements and treatment of skeletal muscle-related diseases.
Asunto(s)
Ácido Ascórbico , Proliferación Celular , Músculo Esquelético , Mioblastos , Factor de Transcripción PAX7 , Regeneración , Animales , Masculino , Ratones , Ácido Ascórbico/farmacología , Línea Celular , Proliferación Celular/efectos de los fármacos , Músculo Esquelético/efectos de los fármacos , Músculo Esquelético/metabolismo , Mioblastos/efectos de los fármacos , Mioblastos/metabolismo , Factor 5 Regulador Miogénico/metabolismo , Factor 5 Regulador Miogénico/genética , Factor de Transcripción PAX7/metabolismo , Factor de Transcripción PAX7/genética , Regeneración/efectos de los fármacos , Células Satélite del Músculo Esquelético/metabolismo , Células Satélite del Músculo Esquelético/efectos de los fármacosRESUMEN
Postexercise skeletal muscle repair is dependent on the actions of satellite cells (SCs). The signal(s) responsible for activation of these normally quiescent cells in the horse remain unknown. The objective of the experiment was to determine whether submaximal exercise or tributyrin (TB) supplementation is sufficient to stimulate SC activation. Adult geldings were fed a control diet (n = 6) or a diet containing 0.45% TB (n = 6). After 30 d, the geldings performed a single bout of submaximal exercise. Middle gluteal muscle biopsies and blood were collected on days -1, 1, 3, and 5 relative to exercise. Diet had no effect on any parameter of physical performance. Total RNA isolated from the gluteal muscle of TB fed geldings contained greater (P < 0.05) amounts of myogenin mRNA than controls. Satellite cell isolates from TB supplemented horses had a greater (P = 0.02) percentage of proliferating cell nuclear antigen immunopositive (PCNA+) SC than controls after 48 h in culture. Submaximal exercise was sufficient to increase (P < 0.05) the percentage of PCNA(+) cells in all isolates obtained during recovery period. No change in the amount of gluteal muscle Pax7 mRNA, a lineage marker of SCs, occurred in response to either diet or exercise. Our results indicate that both submaximal exercise and TB prime SCs for activation and cell cycle reentry but are insufficient to cause an increase in Pax7 expression during the recovery period.
Asunto(s)
Caballos/fisiología , Condicionamiento Físico Animal/fisiología , Triglicéridos/farmacología , Alimentación Animal , Fenómenos Fisiológicos Nutricionales de los Animales , Animales , Dieta/veterinaria , Suplementos Dietéticos , Masculino , Músculo Esquelético/fisiología , Miogenina , Factor de Transcripción PAX7/genética , Factor de Transcripción PAX7/metabolismo , Antígeno Nuclear de Célula en Proliferación/metabolismo , ARN Mensajero/metabolismo , Células Satélite del Músculo Esquelético/fisiología , Triglicéridos/administración & dosificaciónRESUMEN
Satellite cells, a population of skeletal muscular stem cells, are generally recognized as the main and, possibly, the sole source of postnatal muscle regeneration. Previous studies have revealed the potential of low-level laser (LLL) irradiation in promoting satellite cell proliferation, which, thereby, boosts the recovery of skeletal muscle from atrophy. The purpose of this study is to investigate the beneficial effect of LLL on disuse-induced atrophy. The optimal irradiation condition of LLL (808 nm) enhancing the proliferation of Pax7+ve cells, isolated from tibialis anterior (TA) muscle, was examined and applied on TA muscle of disuse-induced atrophy model of the rats accordingly. Healthy rats were used as the control. On one hand, transiently, LLL was able to postpone the progression of atrophy for 1 week through a reduction of apoptosis in Pax7-veMyoD+ve (myocyte) population. Simultaneously, a significant enhancement was observed in Pax7+veMyoD+ve population; however, most of the increased cells underwent apoptosis since the second week, which suggested an impaired maturation of the population. On the other hand, in normal control rats with LLL irradiation, a significant increase in Pax7+veMyoD+ve cells and a significant decrease of apoptosis were observed. As a result, a strengthened muscle contraction was observed. Our data showed the capability of LLL in postponing the progression of disuse-induced atrophy for the first time. Furthermore, the result of normal rats with LLL irradiation showed the effectiveness of LLL to strengthen muscle contraction in healthy control.
Asunto(s)
Terapia por Luz de Baja Intensidad , Trastornos Musculares Atróficos/radioterapia , Animales , Apoptosis , Proliferación Celular/efectos de la radiación , Modelos Animales de Enfermedad , Masculino , Contracción Muscular , Músculo Esquelético/patología , Músculo Esquelético/fisiopatología , Factor de Transcripción PAX7/metabolismo , Ratas Sprague-DawleyRESUMEN
BACKGROUND: Recent studies have highlighted the JAK/STAT signaling pathway in the regulation of muscle satellite cell behavior. Herein we report preclinical studies designed to characterize the effects of a novel JAK/STAT inhibitor on plantar flexor skeletal muscle function, morphology, and satellite cell content. METHODS: The compound, SGI-1252, was administered orally (400mg/kg) in a 10% dextrose solution to wild type mice (n = 6) 3 times per week for 8 weeks. A control group (n = 6) received only the dextrose solution. RESULTS: SGI-1252 was well tolerated, as animals displayed similar weight gain over the 8-week treatment period. Following treatment, fatigue in the gastrocnemius-soleus-plantaris complex was greater in the SGI-1252 mice during a 300 second tetanic contraction bout (p = 0.035), though both the rate of fatigue and maximal force production were similar. SGI-1252 treated mice had increased type II myofiber cross-sectional area (1434.8 ± 225.4 vs 1754.7 ± 138.5 µm2), along with an increase in wet muscle mass (125.45 ± 5.46 vs 139.6 ± 12.34 mg, p = 0.032) of the gastrocnemius relative to vehicle treated mice. SGI-1252 treatment reduced gastrocnemius STAT3 phosphorylation 53% (94.79 ± 45.9 vs 44.5 ± 6.1 MFI) and significantly increased the concentration of Pax7+ satellite cells (2589.2 ± 105.5 vs 2859.4 ± 177.5 SC/mm3) in the gastrocnemius. SGI-1252 treatment suppressed MyoD (p = 0.013) and Myogenin (p<0.0001) expression in human primary myoblasts, resulting in reduced myogenic differentiation (p = 0.039). CONCLUSIONS: Orally delivered SGI-1252 was well tolerated, attenuates skeletal muscle STAT3 activity, and increases satellite cell content in mouse gastrocnemius muscle, likely by inhibiting myogenic progression.
Asunto(s)
Diaminas/farmacología , Quinasas Janus/metabolismo , Músculo Esquelético/efectos de los fármacos , Inhibidores de Proteínas Quinasas/farmacología , Pirimidinas/farmacología , Factores de Transcripción STAT/metabolismo , Administración Oral , Animales , Diferenciación Celular/efectos de los fármacos , Proliferación Celular/efectos de los fármacos , Esquema de Medicación , Evaluación Preclínica de Medicamentos , Humanos , Quinasas Janus/antagonistas & inhibidores , Ratones , Ratones Endogámicos C57BL , Músculo Esquelético/metabolismo , Músculo Esquelético/patología , Proteína MioD/metabolismo , Mioblastos/citología , Mioblastos/efectos de los fármacos , Mioblastos/metabolismo , Miogenina/metabolismo , Factor de Transcripción PAX7/metabolismo , Fosforilación/efectos de los fármacos , Factores de Transcripción STAT/antagonistas & inhibidores , Células Satélite del Músculo Esquelético/citología , Células Satélite del Músculo Esquelético/efectos de los fármacos , Células Satélite del Músculo Esquelético/metabolismoRESUMEN
Aged skeletal muscle has an attenuated and delayed ability to proliferate satellite cells in response to resistance exercise. The mechanistic target of rapamycin complex 1 (mTORC1) signaling pathway is a focal point for cell growth, however, the effect of postexercise mTORC1 activation on human skeletal muscle satellite cell (SC) proliferation is unknown. To test the proliferative capacity of skeletal muscle SC in aging muscle to a potent mTORC1 activator (i.e., EAA; essential amino acids) we recruited older (~72y) men to conduct leg resistance exercise (8setsx10reps) without (-EAA; n = 8) and with (+EAA: n = 11) ingestion of 10 g of EAA 1 h postexercise. Muscle biopsies were taken before exercise (Pre) and 24 h postexercise (Post) for assessment of expression and fiber type-specific Pax7+ SC, Ki67+Pax7+ SC and MyoD+ SC -EAA did not show an increase in Pax7+ satellite cells at Post(P > 0.82). Although statistical significance for an increase in Pax7 + SC at 24 h post-RE was not observed in +EAA versus -EAA, we observed trends for a treatment difference (P < 0.1). When examining the change from Pre to Post trends were demonstrated (#/myofiber: P = 0.076; and %/myonuclei: P = 0.065) for a greater increase in +EAA versus -EAA Notably, we found an increase SC proliferation in +EAA, but not -EAA with increase in Ki67+ SC and MyoD+ cells (P < 0.05). Ki67+ SC also exhibited a significant group difference Post (P < 0.010). Pax7+ SC in fast twitch myofibers did not change and were not different between groups (P > 0.10). CDK2, MEF2C, RB1 mRNA only increased in +EAA (P < 0.05). Acute muscle satellite cell proliferative capacity may be partially rescued with postexercise EAA ingestion in older men.
Asunto(s)
Aminoácidos Esenciales/farmacología , Proliferación Celular , Músculo Esquelético/efectos de los fármacos , Entrenamiento de Fuerza , Células Satélite del Músculo Esquelético/efectos de los fármacos , Anciano , Aminoácidos Esenciales/administración & dosificación , Estudios de Casos y Controles , Quinasa 2 Dependiente de la Ciclina/genética , Quinasa 2 Dependiente de la Ciclina/metabolismo , Suplementos Dietéticos , Humanos , Antígeno Ki-67/genética , Antígeno Ki-67/metabolismo , Masculino , Músculo Esquelético/metabolismo , Músculo Esquelético/fisiología , Proteína MioD/genética , Proteína MioD/metabolismo , Factor de Transcripción PAX7/genética , Factor de Transcripción PAX7/metabolismo , Proteínas de Unión a Retinoblastoma/genética , Proteínas de Unión a Retinoblastoma/metabolismo , Células Satélite del Músculo Esquelético/metabolismo , Células Satélite del Músculo Esquelético/fisiología , Ubiquitina-Proteína Ligasas/genética , Ubiquitina-Proteína Ligasas/metabolismoRESUMEN
Supplementation of micronutrients involved in DNA methylation, particularly during pregnancy, is recommended because of its impacts on human health, but further evidence is needed regarding the effects of over-supplementation and differences between sexes. Here, a porcine model was used to assess effects of maternal supplementation with one-carbon-cycle compounds during prenatal and postnatal stages on offspring muscle development. Sows received either a standard diet (CON) or a standard diet supplemented with folate, B6, B12, methionine, choline, and zinc (MET) throughout gestation. Myogenesis-, growth-, and nutrient utilization-related transcript expression was assessed using quantitative PCR. Organismal phenotype and gene expression effects differed significantly between males and females. Male MET-offspring showed increased fetal weight during late pregnancy but decreased live weight postnatally, with compensatory transcriptional responses comprising myogenic key drivers (Pax7, MyoD1, myogenin). In contrast, female weights were unaffected by diet, and mRNA abundances corresponded to a phenotype of cellular reorganization via FABP3, FABP4, SPP1 and Insulin-like Growth Factor-signaling. These findings in an animal model suggest that supplementation during pregnancy with methylation-related micronutrients can promote sex-specific myogenic maturation processes related to organismal growth and muscle metabolism. The usage of maternal dietary supplements should be more carefully considered regarding its ability to promote fetal and postnatal health.
Asunto(s)
Fenómenos Fisiológicos Nutricionales de los Animales , Dieta/veterinaria , Fenómenos Fisiologicos Nutricionales Maternos , Micronutrientes/administración & dosificación , Desarrollo de Músculos/efectos de los fármacos , Factores Sexuales , Alimentación Animal/análisis , Animales , Animales Recién Nacidos , Metilación de ADN/efectos de los fármacos , Proteínas de Unión a Ácidos Grasos/genética , Proteínas de Unión a Ácidos Grasos/metabolismo , Femenino , Feto , Expresión Génica , Masculino , Técnicas Analíticas Microfluídicas , Modelos Animales , Proteína MioD/genética , Proteína MioD/metabolismo , Miogenina/genética , Miogenina/metabolismo , Osteopontina/genética , Osteopontina/metabolismo , Factor de Transcripción PAX7/genética , Factor de Transcripción PAX7/metabolismo , Embarazo , Reproducibilidad de los Resultados , PorcinosRESUMEN
OBJECTIVE: To observe the effect of electroacupuncture (EA) serum on proliferation of multifidus muscle sa-tellite cells (SCs) and expression of paired box transcription factor Pax-7, MyoD and protein kinase B (PKB or Akt) proteins of SCs, so as to explore its underlying mechanism in promoting repair of multifidus muscles. METHODS: Thirty-two SD rats were randomly assigned to control, model, EA-Weizhong (BL 40) and EA-Shenshu (BL 23) groups. The multifidus muscle injury (MFMI) model was established by injection of 0.5% bupivacaine hydrochloride (400 µL) into the bilateral L4-L5 paravertebral muscles (4 points, 100 µL for each point). EA stimulation was separately applied to bilateral BL 40 and BL 23 for 20 min, once daily, 4 days altogether. Blood samples of the abdominal artery of rats in the above mentioned 4 groups were separately collected for extracting serum, followed by deactivation and filtration, and then were respectively applied to the Dulbecco's Modified Eagle Media (DMEM) culturing each multifidus muscle SCs of the normal serum, model serum, EA-BL 40 serum and EA-BL 40 serum+LY 294002 (an inhibitor of phosphotidylinsitol-3-kinase, PI 3 K), EA-BL 23 serum and EA-BL 23 serum+LY 294002 groups for ana-lyzing the impact of EA serum on the proliferation state of SCs by Cell Counting Kit-8 (CCK-8) and 5-Ethynyl-2'-deoxyuridine (EdU) methods, respectively. The expression of Pax-7, MyoD and phosphorylated (p)-Akt proteins of the cultured SCs was detected for characterization of SCs by Western blot. RESULTS: Compared with the normal serum group, the proliferation levels (detected by both CCK-8- and EdU) and the expression levels of MyoD and p-Akt proteins of SCs in the model serum group were significantly increased (P<0.05, P<0.01), while in comparison with the model serum group, the proliferation and expression levels of MyoD and p-Akt proteins of SCs were further significantly increased in both EA-BL 23 and EA-BL 40 serum groups (P<0.01, P<0.05), but not in the EA-BL 40 serum+LY 294002 and EA-BL 23 serum+LY 294002 groups (P>0.05), suggesting an involvement of PI 3 K in the proliferation of SCs. No marked differences were found in the proliferation levels between the EA-BL 23 and EA-BL 40 serum groups and in the expression levels of Pax-7 proteins among the 6 serum groups (P>0.05). CONCLUSIONS: Both EA-BL 40 and EA-BL 23 serum can promote proliferation of multifidus muscle SCs, which may contribute to the effect of EA intervention in promoting repair of the injured muscle, partially by way of Akt/PI 3 K signaling.
Asunto(s)
Electroacupuntura , Músculos/lesiones , Enfermedades Musculares/terapia , Proteína MioD/genética , Proteína Oncogénica v-akt/genética , Factor de Transcripción PAX7/genética , Células Satélite del Músculo Esquelético/citología , Suero/química , Puntos de Acupuntura , Animales , Proliferación Celular , Humanos , Masculino , Músculos/metabolismo , Enfermedades Musculares/genética , Enfermedades Musculares/metabolismo , Proteína MioD/metabolismo , Proteína Oncogénica v-akt/metabolismo , Factor de Transcripción PAX7/metabolismo , Ratas Sprague-Dawley , Células Satélite del Músculo Esquelético/metabolismo , Transducción de SeñalRESUMEN
Human skeletal muscle satellite cells (SCs) are essential for muscle regeneration and remodeling processes in healthy and clinical conditions involving muscle breakdown. However, the potential influence of protein supplementation on post-exercise SC regulation in human skeletal muscle has not been well investigated. In a comparative human study, we investigated the effect of hydrolyzed whey protein supplementation following eccentric exercise on fiber type-specific SC accumulation. Twenty-four young healthy subjects received either hydrolyzed whey protein + carbohydrate (whey, n = 12) or iso-caloric carbohydrate (placebo, n = 12) during post-exercise recovery from 150 maximal unilateral eccentric contractions. Prior to and 24, 48 and 168 h post-exercise, muscle biopsies were obtained from the exercise leg and analyzed for fiber type-specific SC content. Maximal voluntary contraction (MVC) and serum creatine kinase (CK) were evaluated as indices of recovery from muscle damage. In type II fiber-associated SCs, the whey group increased SCs/fiber from 0.05 [0.02; 0.07] to 0.09 [0.06; 0.12] (p < 0.05) and 0.11 [0.06; 0.16] (p < 0.001) at 24 and 48 h, respectively, and exhibited a difference from the placebo group (p < 0.05) at 48 h. The whey group increased SCs/myonuclei from 4 % [2; 5] to 10 % [4; 16] (p < 0.05) at 48 h, whereas the placebo group increased from 5 % [2; 7] to 9 % [3; 16] (p < 0.01) at 168 h. MVC decreased (p < 0.001) and muscle soreness and CK increased (p < 0.001), irrespective of supplementation. In conclusion, whey protein supplementation may accelerate SC proliferation as part of the regeneration or remodeling process after high-intensity eccentric exercise.
Asunto(s)
Suplementos Dietéticos , Ejercicio Físico/fisiología , Proteínas de la Leche/química , Músculos/fisiología , Adulto , Proliferación Celular , Creatina Quinasa/sangre , Estudios Cruzados , Dieta , Método Doble Ciego , Humanos , Hidrólisis , Inmunohistoquímica , Contracción Isométrica , Masculino , Contracción Muscular , Músculo Esquelético/metabolismo , Factor de Transcripción PAX7/metabolismo , Regeneración , Factores de Tiempo , Proteína de Suero de Leche , Adulto JovenRESUMEN
In the developing chick hypothalamus, Shh and BMPs are expressed in a spatially overlapping, but temporally consecutive, manner. Here, we demonstrate how the temporal integration of Shh and BMP signalling leads to the late acquisition of Pax7 expression in hypothalamic progenitor cells. Our studies reveal a requirement for a dual action of BMPs: first, the inhibition of GliA function through Gli3 upregulation; and second, activation of a Smad5-dependent BMP pathway. Previous studies have shown a requirement for spatial antagonism of Shh and BMPs in early CNS patterning; here, we propose that neural pattern elaboration can be achieved through a versatile temporal antagonism between Shh and BMPs.