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Conditional deletion of Mbtps1 (cKO) protease in bone osteocytes leads to an age-related increase in mass (12%) and in contractile force (30%) in adult slow twitch soleus muscles (SOL) with no effect on fast twitch extensor digitorum longus muscles. Surprisingly, bone from 10-12-month-old cKO animals was indistinguishable from controls in size, density, and morphology except for a 25% increase in stiffness. cKO SOL exhibited increased expression of Pax7, Myog, Myod1, Notch, and Myh3 and 6-fold more centralized nuclei, characteristics of postnatal regenerating muscle, but only in type I myosin heavy chain-expressing cells. Increased expression of gene pathways mediating EGF receptor signaling, circadian exercise, striated muscle contraction, and lipid and carbohydrate oxidative metabolism were also observed in cKO SOL. This muscle phenotype was not observed in 3-month-old mice. Although Mbtps1 mRNA and protein expression was reduced in cKO bone osteocytes, no differences in Mbtps1 or cre recombinase expression were observed in cKO SOL, explaining this age-related phenotype. Understanding bone-muscle cross-talk may provide a fresh and novel approach to prevention and treatment of age-related muscle loss.
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Desenvolvimento Muscular , Músculo Esquelético/metabolismo , Fatores de Regulação Miogênica/metabolismo , Osteócitos/enzimologia , Pró-Proteína Convertases/metabolismo , Sarcopenia/metabolismo , Serina Endopeptidases/metabolismo , Fatores de Transcrição/metabolismo , Animais , Cruzamentos Genéticos , Metabolismo Energético , Perfilação da Expressão Gênica , Regulação da Expressão Gênica no Desenvolvimento , Masculino , Camundongos Knockout , Contração Muscular , Fibras Musculares de Contração Lenta/metabolismo , Fibras Musculares de Contração Lenta/patologia , Força Muscular , Músculo Esquelético/patologia , Desenvolvimento Musculoesquelético , Fatores de Regulação Miogênica/genética , Osteócitos/metabolismo , Osteócitos/patologia , Pró-Proteína Convertases/genética , RNA Mensageiro/metabolismo , Sarcopenia/patologia , Serina Endopeptidases/genética , Fatores de Transcrição/genéticaRESUMO
The ability of skeletal muscle to enhance lipid utilization during exercise is a form of metabolic plasticity essential for survival. Conversely, metabolic inflexibility in muscle can cause organ dysfunction and disease. Although the transcription factor Kruppel-like factor 15 (KLF15) is an important regulator of glucose and amino acid metabolism, its endogenous role in lipid homeostasis and muscle physiology is unknown. Here we demonstrate that KLF15 is essential for skeletal muscle lipid utilization and physiologic performance. KLF15 directly regulates a broad transcriptional program spanning all major segments of the lipid-flux pathway in muscle. Consequently, Klf15-deficient mice have abnormal lipid and energy flux, excessive reliance on carbohydrate fuels, exaggerated muscle fatigue, and impaired endurance exercise capacity. Elucidation of this heretofore unrecognized role for KLF15 now implicates this factor as a central component of the transcriptional circuitry that coordinates physiologic flux of all three basic cellular nutrients: glucose, amino acids, and lipids.
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Exercício Físico , Fatores de Transcrição Kruppel-Like/fisiologia , Metabolismo dos Lipídeos , Músculo Esquelético/metabolismo , Proteínas Nucleares/fisiologia , Aminoácidos/metabolismo , Glucose/metabolismo , Homeostase , HumanosRESUMO
BACKGROUND: Loss of muscle mass and strength (i.e., sarcopenia) in the older adults is a strong predictor of falls, with subsequent morbidity and inability to execute activities of daily living. Use of biomarkers may enhance assessment of effects of community-based exercise interventions aimed at improving muscle strength. OBJECTIVE: The aim of this study was to investigate the use of troponin as a newly proposed biomarker of skeletal muscle health when determining the outcomes of strength-training programs designed for community-dwelling adults over the age of 65 years. METHODS: Outcomes of two strength training programs ("Peer Exercise Program Promotes Independence" and "Stay Strong, Stay Healthy") were assessed using physical performance tests designed for senior fitness evaluation, grip strength, and changes in serum levels of skeletal muscle-specific troponin T (sTnT). RESULTS: Improvement in physical performance, including a significant increase in grip strength, was associated with a significant reduction in serum levels of sTnT. DISCUSSION: Findings from these studies suggest that, when "Peer Exercise Program Promotes Independence" and "Stay Strong, Stay Healthy" are implemented for at least 10 weeks, significant gains in strength are achieved. This strength improvement was associated with a reduction in serum levels of troponin, supporting the use of troponin as a novel biomarker of muscle health in the assessment of strength training programs for the older adults. Reduced sTnT after exercise intervention suggests that skeletal muscles become stronger and less susceptible to damage because of the exercise regimens.
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Acidentes por Quedas/prevenção & controle , Força Muscular/fisiologia , Músculo Esquelético/metabolismo , Treinamento Resistido , Troponina T/sangue , Fatores Etários , Idoso , Idoso de 80 Anos ou mais , Biomarcadores/sangue , Feminino , Nível de Saúde , Humanos , Masculino , Avaliação de Resultados em Cuidados de Saúde , Suporte de Carga/fisiologiaRESUMO
Bioactive lipids have been identified as dynamic signaling lipid mediators (LMs). These fats have the ability to activate responses and control bodily functions either directly or indirectly. Linoleic Acid (LA) and Alpha Linoleic Acid (ALA) are types of omega 3 fatty acids that possess inflammatory properties and promote resolution of inflammation either through their own actions or through their metabolites known as oxylipins. In this chapter, we provide an explanation of a method that combines chromatography with tandem mass spectroscopy (LC MS/MS) to identify and measure all the metabolites derived from LA and ALA. Additionally, we employed the described methodology to analyze human serum samples obtained before and after whole-body vibration exercise training. The results indicated an increase in some of the LA and ALA LMs that have beneficial effects in regulating the cardiovascular system.
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Ácido Linoleico , Lipidômica , Espectrometria de Massas em Tandem , Vibração , Humanos , Ácido Linoleico/metabolismo , Lipidômica/métodos , Espectrometria de Massas em Tandem/métodos , Cromatografia Líquida/métodos , Exercício Físico/fisiologia , Oxilipinas/metabolismo , Oxilipinas/sangue , Metabolismo dos LipídeosRESUMO
Developing robust analytical techniques is a vital phase to facilitate understanding the roles and impacts of various omic profilings in cellular functions. The comprehensive analysis of various biological molecules within a biological system requires a precise sample preparation technique. Solid-Phase Extraction (SPE) has proven to be an indispensable method in lipidomic analysis, providing an uncomplicated and user-friendly technique for extraction and purification of lipid components from complex biological matrices. Of all the factors influencing the reliability and success of SPE, column or adsorbent materials, flow rate, and storage conditions are paramount in terms of their significance. In this chapter, we will discuss in detail the SPE steps for lipidomic analysis in biofluid samples (serum and plasma) and muscle tissues.
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Lipidômica , Lipídeos , Extração em Fase Sólida , Extração em Fase Sólida/métodos , Lipidômica/métodos , Lipídeos/isolamento & purificação , Lipídeos/química , Humanos , AnimaisRESUMO
In this review, we explore the application of novel biomaterial-based therapies specifically targeted towards craniofacial bone defects. The repair and regeneration of critical sized bone defects in the craniofacial region requires the use of bioactive materials to stabilize and expedite the healing process. However, the existing clinical approaches face challenges in effectively treating complex craniofacial bone defects, including issues such as oxidative stress, inflammation, and soft tissue loss. Given that a significant portion of individuals affected by traumatic bone defects in the craniofacial area belong to the aging population, there is an urgent need for innovative biomaterials to address the declining rate of new bone formation associated with age-related changes in the skeletal system. This article emphasizes the importance of semiconductor industry-derived materials as a potential solution to combat oxidative stress and address the challenges associated with aging bone. Furthermore, we discuss various material and autologous treatment approaches, as well as in vitro and in vivo models used to investigate new therapeutic strategies in the context of craniofacial bone repair. By focusing on these aspects, we aim to shed light on the potential of advanced biomaterials to overcome the limitations of current treatments and pave the way for more effective and efficient therapeutic interventions for craniofacial bone defects.
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Isolated individual myofibers are valuable experimental models that can be used in various conditions to understand skeletal muscle physiology and pathophysiology at the tissue and cellular level. This report details a time- and cost-effective method for isolation of single myofibers from the flexor digitorum brevis (FDB) muscle in both young and aged mice. The FDB muscle was chosen for its documented history in single myofiber experiments. By modifying published methods for FDB myofiber isolation, we have optimized the protocol by first separating FDB muscle into individual bundles before the digestion, followed by optimizing the subsequent digestion medium conditions to ensure reproducibility. Morphological and functional assessments demonstrate a high yield of isolated FDB myofibers with sarcolemma integrity achieved in a shorter time frame than previous published procedures. This method could be also adapted to other types of skeletal muscle. Additionally, this highly reproducible method can greatly reduce the number of animals needed to yield adequate numbers of myofibers for experiments. Thus, this advanced method for myofiber isolation has the potential to accelerate research in skeletal muscle physiology and screening potential therapeutics "ex vivo" for muscle diseases and regeneration.
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Fibras Musculares Esqueléticas , Músculo Esquelético , Camundongos , Animais , Reprodutibilidade dos TestesRESUMO
Diabetes is characterized by ventilatory depression due to decreased diaphragm (DPH) function. This study investigated the changes in contractile properties of rat DPH muscles over a time interval encompassing from 4 days to 14 weeks after the onset of streptozotocin-induced diabetes, with and without insulin treatment for 2 weeks. Maximum tetanic force in intact DPH muscle strips and recovery from fatiguing stimulation were measured. An early (4-day) depression in contractile function in diabetic DPH was followed by gradual improvement in muscle function and fatigue recovery (8 weeks). DPH contractile function deteriorated again at 14 weeks, a process that was completely reversed by insulin treatment. Maximal contractile force and calcium sensitivity assessed in Triton-skinned DPH fibers showed a similar bimodal pattern and the same beneficial effect of insulin treatment. While an extensive analysis of the isoforms of the contractile and regulatory proteins was not conducted, Western blot analysis of tropomyosin suggests that the changes in diabetic DPH response depended, at least in part, on a switch in fiber type.
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Adaptação Fisiológica/fisiologia , Diabetes Mellitus Experimental/metabolismo , Diafragma , Contração Muscular , Fadiga Muscular , Análise de Variância , Animais , Diafragma/metabolismo , Diafragma/fisiopatologia , Masculino , Isoformas de Proteínas/química , Isoformas de Proteínas/metabolismo , Ratos , Ratos Sprague-Dawley , Estreptozocina , Tropomiosina/química , Tropomiosina/metabolismoRESUMO
Osteoporosis and sarcopenia (osteosarcopenia (OS)) are twin-aging diseases. The biochemical crosstalk between muscle and bone seems to play a role in OS. We have previously shown that osteocytes produce soluble factors with beneficial effects on muscle and vice versa. Recently, enhanced FGF9 production was observed in the OmGFP66 osteogenic cell line. To test its role in myogenic differentiation, C2C12 myoblasts were treated with recombinant FGF9. FGF9 as low as 10 ng/mL inhibited myogenic differentiation, suggesting that FGF9 might be a potential inhibitory factor produced from bone cells with effects on muscle cells. FGF9 (10-50 ng/mL) significantly decreased mRNA expression of MyoG and Mhc while increasing the expression of Myostatin. Consistent with the phenotype, RT-qPCR array revealed that FGF9 (10 ng/mL) increased the expression of Icam1 while decreased the expression of Wnt1 and Wnt6 decreased, respectively. FGF9 decreased caffeine-induced Ca2+ release from the sarcoplasmic reticulum (SR) of C2C12 myotubes and reduced the expression of genes (i.e. Cacna1s, RyR2, Naftc3) directly associated with intracellular Ca2+ homeostasis. Myogenic differentiation in human skeletal muscle cells was similarly inhibited by FGF9 but required higher doses of 200 ng/mL FGF9. FGF9 was also shown to stimulate C2C12 myoblast proliferation. FGF2 and the FGF9 subfamily members FGF16 and FGF20 also inhibited C2C12 myoblast differentiation and enhanced proliferation. Intriguingly, the differentiation inhibition was independent of proliferation enhancement. These findings suggest that FGF9 may modulate myogenesis via a complex signaling mechanism.
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Fator 9 de Crescimento de Fibroblastos/fisiologia , Desenvolvimento Muscular/fisiologia , Fibras Musculares Esqueléticas/citologia , Animais , Cafeína/farmacologia , Cálcio/metabolismo , Linhagem Celular , Proliferação de Células , Células Cultivadas , Fatores de Crescimento de Fibroblastos/fisiologia , Regulação da Expressão Gênica , Humanos , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Desenvolvimento Muscular/genética , Biogênese de Organelas , Regeneração , Retículo Sarcoplasmático/efeitos dos fármacos , Retículo Sarcoplasmático/metabolismo , Transdução de SinaisRESUMO
We examined the effects of osteocyte secreted factors on myogenesis and muscle function. MLO-Y4 osteocyte-like cell conditioned media (CM) (10%) increased ex vivo soleus muscle contractile force by ~25%. MLO-Y4 and primary osteocyte CM (1-10%) stimulated myogenic differentiation of C2C12 myoblasts, but 10% osteoblast CMs did not enhance C2C12 cell differentiation. Since WNT3a and WNT1 are secreted by osteocytes, and the expression level of Wnt3a is increased in MLO-Y4 cells by fluid flow shear stress, both were compared, showing WNT3a more potent than WNT1 in inducing myogenesis. Treatment of C2C12 myoblasts with WNT3a at concentrations as low as 0.5ng/mL mirrored the effects of both primary osteocyte and MLO-Y4 CM by inducing nuclear translocation of ß-catenin with myogenic differentiation, suggesting that Wnts might be potential factors secreted by osteocytes that signal to muscle cells. Knocking down Wnt3a in MLO-Y4 osteocytes inhibited the effect of CM on C2C12 myogenic differentiation. Sclerostin (100ng/mL) inhibited both the effects of MLO-Y4 CM and WNT3a on C2C12 cell differentiation. RT-PCR array results supported the activation of the Wnt/ß-catenin pathway by MLO-Y4 CM and WNT3a. These results were confirmed by qPCR showing up-regulation of myogenic markers and two Wnt/ß-catenin downstream genes, Numb and Flh1. We postulated that MLO-Y4 CM/WNT3a could modulate intracellular calcium homeostasis as the trigger mechanism for the enhanced myogenesis and contractile force. MLO-Y4 CM and WNT3a increased caffeine-induced Ca2+ release from the sarcoplasmic reticulum (SR) of C2C12 myotubes and the expression of genes directly associated with intracellular Ca2+ signaling and homeostasis. Together, these data show that in vitro and ex vivo, osteocytes can stimulate myogenesis and enhance muscle contractile function and suggest that Wnts could be mediators of bone to muscle signaling, likely via modulation of intracellular Ca2+ signaling and the Wnt/ß-Catenin pathway.
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There is growing evidence that severe decline of skeletal muscle mass and function with age may be mitigated by exercise and dietary supplementation with protein and amino acid ingredient technologies. The purposes of this study were to examine the effects of the leucine catabolite, beta-hydroxy-beta-methylbutyrate (HMB), in C2C12 myoblasts and myotubes, and to investigate the effects of dietary supplementation with HMB, the amino acid ß-alanine and the combination thereof, on muscle contractility in a preclinical model of pre-sarcopenia. In C2C12 myotubes, HMB enhanced sarcoplasmic reticulum (SR) calcium release beyond vehicle control in the presence of all SR agonists tested (KCl, P<0.01; caffeine, P = 0.03; ionomycin, P = 0.03). HMB also improved C2C12 myoblast viability (25 µM HMB, P = 0.03) and increased proliferation (25 µM HMB, P = 0.04; 125 µM HMB, P<0.01). Furthermore, an ex vivo muscle contractility study was performed on EDL and soleus muscle from 19 month old, male C57BL/6nTac mice. For 8 weeks, mice were fed control AIN-93M diet, diet with HMB, diet with ß-alanine, or diet with HMB and ß-alanine. In ß-alanine fed mice, EDL muscle showed a 7% increase in maximum absolute force compared to the control diet (202 ± 3vs. 188± 5 mN, P = 0.02). At submaximal frequency of stimulation (20 Hz), EDL from mice fed HMB plus ß-alanine showed an 11% increase in absolute force (88.6 ± 2.2 vs. 79.8 ± 2.4 mN, P = 0.025) and a 13% increase in specific force (12.2 ± 0.4 vs. 10.8 ± 0.4 N/cm2, P = 0.021). Also in EDL muscle, ß-alanine increased the rate of force development at all frequencies tested (P<0.025), while HMB reduced the time to reach peak contractile force (TTP), with a significant effect at 80 Hz (P = 0.0156). In soleus muscle, all experimental diets were associated with a decrease in TTP, compared to control diet. Our findings highlight beneficial effects of HMB and ß-alanine supplementation on skeletal muscle function in aging mice.
Assuntos
Envelhecimento/metabolismo , Butiratos/farmacologia , Sinalização do Cálcio/efeitos dos fármacos , Suplementos Nutricionais , Fibras Musculares Esqueléticas/metabolismo , beta-Alanina/farmacologia , Envelhecimento/genética , Envelhecimento/patologia , Animais , Sinalização do Cálcio/genética , Linhagem Celular , Masculino , Camundongos , Camundongos Transgênicos , Contração Muscular/efeitos dos fármacos , Contração Muscular/genética , Fibras Musculares Esqueléticas/patologia , Força Muscular/efeitos dos fármacos , Força Muscular/genética , Retículo Sarcoplasmático/genética , Retículo Sarcoplasmático/metabolismo , Retículo Sarcoplasmático/patologiaRESUMO
Falling is a significant health issue among elderly adults. Given the multifactorial nature of falls, effective balance and fall risk assessment must take into account factors from multiple sources. Here we investigate the relationship between fall risk and a diverse set of biochemical and biomechanical variables including: skeletal muscle-specific troponin T (sTnT), maximal strength measures derived from isometric grip and leg extension tasks, and postural sway captured from a force platform during a quiet stance task. These measures were performed in eight young and eleven elderly adults, along with estimates of fall risk derived from the Tinetti Balance Assessment. We observed age-related effects in all measurements, including a trend toward increased sTnT levels, increased postural sway, reduced upper and lower extremity strength, and reduced balance scores. We observed a negative correlation between balance scores and sTnT levels, suggesting its use as a biomarker for fall risk. We observed a significant positive correlation between balance scores and strength measures, adding support to the notion that muscle strength plays a significant role in postural control. We observed a significant negative correlation between balance scores and postural sway, suggesting that fall risk is associated with more loosely controlled center of mass regulation.
Assuntos
Acidentes por Quedas , Envelhecimento/fisiologia , Força Muscular/fisiologia , Músculo Esquelético/fisiologia , Equilíbrio Postural/fisiologia , Adulto , Idoso de 80 Anos ou mais , Fenômenos Biomecânicos , Feminino , Humanos , Prognóstico , Fatores de Risco , Adulto JovemRESUMO
Autosomal recessive hypophosphatemic rickets (ARHR) is a heritable disorder characterized by hypophosphatemia, osteomalacia, and poor bone development. ARHR results from inactivating mutations in the DMP1 gene with the human phenotype being recapitulated in the Dmp1 null mouse model which displays elevated plasma fibroblast growth factor 23. While the bone phenotype has been well-characterized, it is not known what effects ARHR may also have on skeletal, cardiac, or vascular smooth muscle function, which is critical to understand in order to treat patients suffering from this condition. In this study, the extensor digitorum longus (EDL-fast-twitch muscle), soleus (SOL-slow-twitch muscle), heart, and aorta were removed from Dmp1 null mice and ex-vivo functional tests were simultaneously performed in collaboration by three different laboratories. Dmp1 null EDL and SOL muscles produced less force than wildtype muscles after normalization for physiological cross sectional area of the muscles. Both EDL and SOL muscles from Dmp1 null mice also produced less force after the addition of caffeine (which releases calcium from the sarcoplasmic reticulum) which may indicate problems in excitation contraction coupling in these mice. While the body weights of the Dmp1 null were smaller than wildtype, the heart weight to body weight ratio was higher. However, there were no differences in pathological hypertrophic gene expression compared to wildtype and maximal force of contraction was not different indicating that there may not be cardiac pathology under the tested conditions. We did observe a decrease in the rate of force development generated by cardiac muscle in the Dmp1 null which may be related to some of the deficits observed in skeletal muscle. There were no differences observed in aortic contractions induced by PGF2α or 5-HT or in endothelium-mediated acetylcholine-induced relaxations or endothelium-independent sodium nitroprusside-induced relaxations. In summary, these results indicate that there are deficiencies in both fast twitch and slow twitch muscle fiber type contractions in this model of ARHR, while there was less of a phenotype observed in cardiac muscle, and no differences observed in aortic function. These results may help explain skeletal muscle weakness reported by some patients with osteomalacia and need to be further investigated.
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Sarcalumenin is a Ca2+-binding protein located in the sarcoplasmic reticulum of striated muscle cells, the physiological function of which has not been fully determined yet. Using sarcalumenin knockout (sar(-/-)) mice, we showed that sar ablation altered store-operated Ca2+ entry (SOCE) and enhanced muscle fatigue resistance. Sar(-/-) mice fatigued less with treadmill exercise, and intact isolated soleus and extensor digitorum longus muscles from sar(-/-) mice were more resistant to intermittent fatiguing stimulation than those from wild-type mice. Enhanced SOCE was observed in the sar(-/-) muscles. Biochemical analysis revealed that sar(-/-) muscles contained significantly elevated expression of mitsugumin 29 (MG29), a synaptophysin-related membrane protein located in the triad junction of skeletal muscle. Because the ablation of mg29 has been shown to cause increased fatigability and dysfunction of SOCE, the enhanced SOCE activity seen in sar(-/-) muscle may be correlated with the increased expression of MG29. Our data suggest that systemic ablation of sarcalumenin caused enhanced resistance to muscle fatigue by compensatory changes in Ca2+ regulatory proteins that effect SOCE.
Assuntos
Cálcio/metabolismo , Proteínas de Membrana/genética , Proteínas de Membrana/fisiologia , Animais , Western Blotting , Membrana Celular/metabolismo , Fadiga , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Camundongos Transgênicos , Modelos Biológicos , Fibras Musculares Esqueléticas/metabolismo , Proteínas Musculares/farmacologia , Músculo Esquelético/metabolismo , Músculos/metabolismo , Mutação , Fenótipo , Condicionamento Físico Animal , Ligação Proteica , Retículo Sarcoplasmático/metabolismo , Sinaptofisina/farmacologia , Fatores de TempoRESUMO
Mitsugumin 29 (MG29) is a transmembrane protein that is normally found in the triad junction of skeletal muscle. Our previous studies have shown that targeted deletion of mg29 from the skeletal muscle resulted in abnormality of the triad junction structure, and also increased susceptibility to muscle fatigue. To elucidate the basis of these effects, we investigated the properties of Ca2+-uptake and -release in toxin-skinned Extensor Digitorium Longus (EDL) muscle fibers from control and mg29 knockout mice. Compared with the control muscle, submaximal Ca2+-uptake into the sarcoplasmic reticulum (SR) was slower and the storage of Ca2+ inside the SR was less in the mutant muscle, due to increased leakage process of Ca2+ movement across the SR. The leakage pathway is associated with the increased sensitivity of Ca2+/caffeine -induced Ca2+ release to myoplasmic Ca2+. Therefore, the increased fatigability of mutant EDL muscles can result from a combination of a slowing of Ca2+ uptake, modification of Ca2+-induced Ca2+ release (CICR), and a reduction in total SR Ca2+ content.
Assuntos
Cálcio/metabolismo , Cálcio/farmacocinética , Homeostase/fisiologia , Fadiga Muscular/fisiologia , Proteínas Musculares/genética , Sinaptofisina/análogos & derivados , Sinaptofisina/genética , Animais , Cafeína/farmacologia , Homeostase/efeitos dos fármacos , Ionomicina/farmacologia , Camundongos , Camundongos Knockout , Fadiga Muscular/efeitos dos fármacos , Fadiga Muscular/genética , Fibras Musculares Esqueléticas/efeitos dos fármacos , Fibras Musculares Esqueléticas/fisiologia , Retículo Sarcoplasmático/efeitos dos fármacos , Retículo Sarcoplasmático/fisiologia , Fatores de TempoRESUMO
Research over the last decade strengthened the understanding that skeletal muscles are not only the major tissue in the body from a volume point of view but also function as a master regulator contributing to optimal organismal health. These new contributions to the available body of knowledge triggered great interest in the roles of skeletal muscle beyond contraction. The World Health Organization, through its Global Burden of Disease (GBD) report, recently raised further awareness about the key importance of skeletal muscles as the GDB reported musculoskeletal (MSK) diseases have become the second greatest cause of disability, with more than 1.7 billion people in the globe affected by a diversity of MSK conditions. Besides their role in MSK disorders, skeletal muscles are also seen as principal metabolic organs with essential contributions to metabolic disorders, especially those linked to physical inactivity. In this review, we have focused on the unique function of new genes/proteins (i.e., MTMR14, MG29, sarcalumenin, KLF15) that during the last few years have helped provide novel insights about muscle function in health and disease, muscle fatigue, muscle metabolism, and muscle aging. Next, we provide an in depth discussion of how these genes/proteins converge into a common function of acting as regulators of intracellular calcium homeostasis. A clear link between dysfunctional calcium homeostasis is established and the special role of store-operated calcium entry is analyzed. The new knowledge that has been generated by the understanding of the roles of previously unknown modulatory genes of the skeletal muscle excitation-contraction coupling (ECC) process brings exciting new possibilities for treatment of MSK diseases, muscle regeneration, and skeletal muscle tissue engineering. The next decade of skeletal muscle and MSK research is bound to bring to fruition applied knowledge that will hopefully offset the current heavy and sad burden of MSK diseases on the planet.
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This paper presents the design and test of a dual-mode electric and magnetic biological stimulator (EM-Stim). The stimulator generates pulsing electric and magnetic fields at programmable rates and intensities. While electric and magnetic stimulators have been reported before, this is the first device that combines both modalities. The ability of the dual stimulation to target bone and muscle tissue simultaneously has the potential to improve the therapeutic treatment of osteoporosis and sarcopenia. The device is fully programmable, portable and easy to use, and can run from a battery or a power supply. The device can generate magnetic fields of up to 1.6 mT and output voltages of +/- 40 V. The EM-Stim accelerated myogenic differentiation of myoblasts into myotubes as evidenced by morphometric, gene expression, and protein content analyses. Currently, there are many patents concerned with the application of single electrical or magnetic stimulation, but none that combine both simultaneously. However, we applied for and obtained a provisional patent for new device to fully explore its therapeutic potential in pre-clinical models.
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Técnicas Citológicas/instrumentação , Técnicas Citológicas/métodos , Estimulação Elétrica/instrumentação , Desenvolvimento Muscular/fisiologia , Mioblastos/citologia , Animais , Diferenciação Celular/fisiologia , Processos de Crescimento Celular/fisiologia , Linhagem Celular , Campos Eletromagnéticos , Humanos , Camundongos , Patentes como AssuntoRESUMO
Described here is a method to measure contractility of isolated skeletal muscles. Parameters such as muscle force, muscle power, contractile kinetics, fatigability, and recovery after fatigue can be obtained to assess specific aspects of the excitation-contraction coupling (ECC) process such as excitability, contractile machinery and Ca(2+) handling ability. This method removes the nerve and blood supply and focuses on the isolated skeletal muscle itself. We routinely use this method to identify genetic components that alter the contractile property of skeletal muscle though modulating Ca(2+) signaling pathways. Here, we describe a newly identified skeletal muscle phenotype, i.e., mechanic alternans, as an example of the various and rich information that can be obtained using the in vitro muscle contractility assay. Combination of this assay with single cell assays, genetic approaches and biochemistry assays can provide important insights into the mechanisms of ECC in skeletal muscle.
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Fadiga/fisiopatologia , Glucanos/fisiologia , Músculo Esquelético/fisiologia , Animais , Sinalização do Cálcio , Camundongos , Contração Muscular/fisiologiaRESUMO
Jatropha curcas (JC) is a multipurpose perennial plant that belongs to the Euphorbiaceae family and is native to arid and semiarid tropical regions worldwide. It has many attributes and considerable potential for renewable energy, fish and livestock feeding. Despite its rich application as a renewable source and for animal feeding, JC has barely been explored for its medicinal potential. Here we review several patents related to JC that show it has been underused for medicinal purposes. For example, only one invention disclosure to date utilizes JC, combined with three other plants, in a preparation for wound healing. Motivated by support from the Brazilian funding agencies and anecdotal accounts in Brazil of the medicinal value of JC, we performed a series of pilot studies that demonstrate that JC is able to protect skeletal muscle cells in vitro against the deleterious effects of ethanol. We were able to determine that JC's effects are mediated by the up regulation of HSP60, a critical mitochondrial heat shock related protein that is essential for intracellular REDOX regulation. Given the fact that ethanol myopathy accounts for more than 50% of all cases of myopathy worldwide, we hope that our studies will sparkle new interest from the scientific community to explore the medicinal properties of Jatropha curcas, including the development of new patents leading to new drugs and new targets for the treatment of muscle diseases and other human diseases.
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Biocombustíveis , Jatropha/química , Plantas Medicinais/química , Animais , Diferenciação Celular/efeitos dos fármacos , Fusão Celular , Forma Celular/efeitos dos fármacos , Sobrevivência Celular/efeitos dos fármacos , Chaperonina 60/metabolismo , Etanol/toxicidade , Humanos , Técnicas In Vitro , Camundongos , Camundongos Endogâmicos C57BL , Células Musculares/efeitos dos fármacos , Células Musculares/metabolismo , Fibras Musculares Esqueléticas/efeitos dos fármacos , Fibras Musculares Esqueléticas/metabolismo , Doenças Musculares/tratamento farmacológico , Doenças Musculares/patologia , Patentes como Assunto , Extratos Vegetais/uso terapêuticoRESUMO
Hyperthermia is an important approach for the treatment of several diseases. Hyperthermia is also thought to induce hypertrophy of skeletal muscles in vitro and in vivo, and has been used as a therapeutic tool for millennia. In the first part of our work, we revise several relevant patents related to the utilization of hyperthermia for the treatment and diagnostic of human diseases. In the second part, we present exciting new data on the effects of forced and natural overexpression of HSP72, using murine in vitro (muscle cells) and ex vivo (primary skeletal muscles) models. These studies help to demonstrate that hyperthermia effects are orchestrated by tight coupling between gene expression, protein function, and intracellular Ca2+ signaling pathways with a key role for calcium-induced calcium release. We hope that the review of current patents along with previous unknown information on molecular signaling pathways that underlie the hypertrophy response to hyperthermia in skeletal muscles may trigger the curiosity of scientists worldwide to explore new inventions that fully utilize hyperthermia for the treatment of muscle diseases.