Academic literature on the topic 'Myotubes humains'
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Journal articles on the topic "Myotubes humains"
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Jacquemin, V., A. Bigot, D. Furling, G. Butler-Browne, and V. Mouly. "L'IGF-1 induit une augmentation de la taille et du contenu en myosine des myotubes humains." Science & Sports 20, no. 4 (August 2005): 199–201. http://dx.doi.org/10.1016/j.scispo.2005.01.011.
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Henrotin, Y., C. Lambert, A. Florin, J. Zappia, P. Centonze, and C. Sanchez. "Évaluation de l’activité des urolithines A et B sur le muscle : modulation transcriptomique sur les myotubes primaires humains." Revue du Rhumatisme 89 (December 2022): A49—A50. http://dx.doi.org/10.1016/j.rhum.2022.10.061.
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Thrush, A. Brianne, Rui Zhang, William Chen, Erin L. Seifert, Jessica K. Quizi, Ruth McPherson, Robert Dent, and Mary-Ellen Harper. "Lower Mitochondrial Proton Leak and Decreased Glutathione Redox in Primary Muscle Cells of Obese Diet-Resistant Versus Diet-Sensitive Humans." Journal of Clinical Endocrinology & Metabolism 99, no. 11 (November 1, 2014): 4223–30. http://dx.doi.org/10.1210/jc.2014-1726.
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Context: Weight loss success in response to energy restriction is highly variable. This may be due in part to differences in mitochondrial function and oxidative stress. Objective: The objective of the study was to determine whether mitochondrial function, content, and oxidative stress differ in well-matched obese individuals in the upper [obese diet sensitive (ODS)] vs lower quintiles [obese diet resistant (ODR)] for rate of weight loss. Design: Primary myotubes derived from muscle biopsies of individuals identified as ODS or ODR were studied. Setting: Compliant ODS and ODR females who completed in the Ottawa Hospital Weight Management Program and identified as ODS and ODR participated in this study. Patients or Other Participants: Eleven ODS and nine ODR weight-stable females matched for age, body mass, and body mass index participated in this study. Intervention: Vastus lateralis muscle biopsies were obtained and processed for muscle satellite cell isolation. Main Outcome Measures: Mitochondrial respiration, content, reactive oxygen species, and glutathione redox ratios were measured in the myotubes of ODS and ODR individuals. Results: Mitochondrial proton leak was increased in myotubes of ODS compared with ODR (P < .05). Reduced and oxidized glutathione was decreased in the myotubes of ODR vs ODS (P < .05), indicating a more oxidized glutathione redox state. There were no differences in myotube mitochondrial content, uncoupling protein 3, or adenine nucleotide translocase levels. Conclusions: Lower rate of mitochondrial proton leak in muscle is a cell autonomous phenomenon in ODR vs ODS individuals, and this is associated with a more oxidized glutathione redox state in ODR vs ODS myotubes. The muscle of ODR subjects may thus have a lower capacity to adapt to oxidative stress as compared with ODS.
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Woo, Jin Seok, Ji-Hye Hwang, Jae-Kyun Ko, Noah Weisleder, Do Han Kim, Jianjie Ma, and Eun Hui Lee. "S165F mutation of junctophilin 2 affects Ca2+ signalling in skeletal muscle." Biochemical Journal 427, no. 1 (March 15, 2010): 125–34. http://dx.doi.org/10.1042/bj20091225.
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JPs (junctophilins) contribute to the formation of junctional membrane complexes in muscle cells by physically linking the t-tubule (transverse-tubule) and SR (sarcoplasmic reticulum) membranes. In humans with HCM (hypertrophic cardiomyopathy), mutations in JP2 are linked to altered Ca2+ signalling in cardiomyocytes; however, the effects of these mutations on skeletal muscle function have not been examined. In the present study, we investigated the role of the dominant-negative JP2-S165F mutation (which is associated with human HCM) in skeletal muscle. Consistent with the hypertrophy observed in human cardiac muscle, overexpression of JP2-S165F in primary mouse skeletal myotubes led to a significant increase in myotube diameter and resting cytosolic Ca2+ concentration. Single myotube Ca2+ imaging experiments showed reductions in both the excitation–contraction coupling gain and RyR (ryanodine receptor) 1-mediated Ca2+ release from the SR. Immunoprecipitation assays revealed defects in the PKC (protein kinase C)-mediated phosphorylation of the JP2-S165F mutant protein at Ser165 and in binding of JP2-S165F to the Ca2+ channel TRPC3 (transient receptor potential cation canonical-type channel 3) on the t-tubule membrane. Therefore both the hypertrophy and altered intracellular Ca2+ signalling in the JP2-S165F-expressing skeletal myotubes can be linked to altered phosphorylation of JP2 and/or altered cross-talk among Ca2+ channels on the t-tubule and SR membranes.
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Pasternak, C., S. Wong, and E. L. Elson. "Mechanical function of dystrophin in muscle cells." Journal of Cell Biology 128, no. 3 (February 1, 1995): 355–61. http://dx.doi.org/10.1083/jcb.128.3.355.
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We have directly measured the contribution of dystrophin to the cortical stiffness of living muscle cells and have demonstrated that lack of dystrophin causes a substantial reduction in stiffness. The inferred molecular structure of dystrophin, its preferential localization underlying the cell surface, and the apparent fragility of muscle cells which lack this protein suggest that dystrophin stabilizes the sarcolemma and protects the myofiber from disruption during contraction. Lacking dystrophin, the muscle cells of persons with Duchenne muscular dystrophy (DMD) are abnormally vulnerable. These facts suggest that muscle cells with dystrophin should be stiffer than similar cells which lack this protein. We have tested this hypothesis by measuring the local stiffness of the membrane skeleton of myotubes cultured from mdx mice and normal controls. Like humans with DMD mdx mice lack dystrophin due to an x-linked mutation and provide a good model for the human disease. Deformability was measured as the resistance to indentation of a small area of the cell surface (to a depth of 1 micron) by a glass probe 1 micron in radius. The stiffness of the membrane skeleton was evaluated as the increment of force (mdyne) per micron of indentation. Normal myotubes with an average stiffness value of 1.23 +/- 0.04 (SE) mdyne/micron were about fourfold stiffer than myotubes cultured from mdx mice (0.34 +/- 0.014 mdyne/micron). We verified by immunofluorescence that both normal and mdx myotubes, which were at a similar developmental stage, expressed sarcomeric myosin, and that dystrophin was detected, diffusely distributed, only in normal, not in mdx myotubes. These results confirm that dystrophin and its associated proteins can reinforce the myotube membrane skeleton by increasing its stiffness and that dystrophin function and, therefore, the efficiency of therapeutic restoration of dystrophin can be assayed through its mechanical effects on muscle cells.
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Morissette, Michael R., Stuart A. Cook, Cattleya Buranasombati, Michael A. Rosenberg, and Anthony Rosenzweig. "Myostatin inhibits IGF-I-induced myotube hypertrophy through Akt." American Journal of Physiology-Cell Physiology 297, no. 5 (November 2009): 1124–32. http://dx.doi.org/10.1152/ajpcell.00043.2009.
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Myostatin is a highly conserved negative regulator of skeletal muscle growth. Loss of functional myostatin in cattle, mice, sheep, dogs, and humans results in increased muscle mass. The molecular mechanisms responsible for this increase in muscle growth are not fully understood. Previously, we have reported that phenylephrine-induced cardiac muscle growth and Akt activation are enhanced in myostatin knockout mice compared with controls. Here we report that skeletal muscle from myostatin knockout mice show increased Akt protein expression and overall activity at baseline secondary to an increase in Akt mRNA. We examined the functional role of myostatin modulation of Akt in C2C12 myotubes, a well-established in vitro model of skeletal muscle hypertrophy. Adenoviral overexpression of myostatin attenuated the insulin-like growth factor-I (IGF-I)-mediated increase in myotube diameter, as well as IGF-I-stimulated Akt phosphorylation. Inhibition of myostatin by overexpression of the NH2-terminal portion of myostatin was sufficient to increase myotube diameter and Akt phosphorylation. Coexpression of myostatin and constitutively active Akt (myr-Akt) restored the increase in myotube diameter. Conversely, expression of dominant negative Akt (dn-Akt) with the inhibitory myostatin propeptide blocked the increase in myotube diameter. Of note, ribosomal protein S6 phosphorylation and atrogin-1/muscle atrophy F box mRNA were increased in skeletal muscle from myostain knockout mice. Together, these data suggest myostatin regulates muscle growth at least in part through regulation of Akt.
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Baquero-Perez, Belinda, Suresh V. Kuchipudi, Jemima Ho, Sujith Sebastian, Anita Puranik, Wendy Howard, Sharon M. Brookes, Ian H. Brown, and Kin-Chow Chang. "Chicken and Duck Myotubes Are Highly Susceptible and Permissive to Influenza Virus Infection." Journal of Virology 89, no. 5 (December 24, 2014): 2494–506. http://dx.doi.org/10.1128/jvi.03421-14.
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ABSTRACTSkeletal muscle, at 30 to 40% of body mass, is the most abundant soft tissue in the body. Besides its primary function in movement and posture, skeletal muscle is a significant innate immune organ with the capacity to produce cytokines and chemokines and respond to proinflammatory cytokines. Little is known about the role of skeletal muscle during systemic influenza A virus infection in any host and particularly avian species. Here we used primary chicken and duck multinucleated myotubes to examine their susceptibility and innate immune response to influenza virus infections. Both chicken and duck myotubes expressed avian and human sialic acid receptors and were readily susceptible to low-pathogenicity (H2N3 A/mallard duck/England/7277/06) and high-pathogenicity (H5N1 A/turkey/England/50-92/91 and H5N1 A/turkey/Turkey/1/05) avian and human H1N1 (A/USSR/77) influenza viruses. Both avian host species produced comparable levels of progeny H5N1 A/turkey/Turkey/1/05 virus. Notably, the rapid accumulation of viral nucleoprotein and matrix (M) gene RNA in chicken and duck myotubes was accompanied by extensive cytopathic damage with marked myotube apoptosis (widespread microscopic blebs, caspase 3/7 activation, and annexin V binding at the plasma membrane). Infected chicken myotubes produced significantly higher levels of proinflammatory cytokines than did the corresponding duck cells. Additionally, in chicken myotubes infected with H5N1 viruses, the induction of interferon beta (IFN-β) and IFN-inducible genes, including the melanoma differentiation-associated protein 5 (MDA-5) gene, was relatively weak compared to infection with the corresponding H2N3 virus. Our findings highlight that avian skeletal muscle fibers are capable of productive influenza virus replication and are a potential tissue source of infection.IMPORTANCEInfection with high-pathogenicity H5N1 viruses in ducks is often asymptomatic, and skeletal muscle from such birds could be a source of infection of humans and animals. Little is known about the ability of influenza A viruses to replicate in avian skeletal muscle fibers. We show here that cultured chicken and duck myotubes were highly susceptible to infection with both low- and high-pathogenicity avian influenza viruses. Infected myotubes of both avian species displayed rapid virus accumulation, apoptosis, and extensive cellular damage. Our results indicate that avian skeletal muscle fibers of chicken and duck could be significant contributors to progeny production of highly pathogenic H5N1 viruses.
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Gundersen, Anders E., Benjamin A. Kugler, Paul M. McDonald, Alexey Veraksa, Joseph A. Houmard, and Kai Zou. "Altered mitochondrial network morphology and regulatory proteins in mitochondrial quality control in myotubes from severely obese humans with or without type 2 diabetes." Applied Physiology, Nutrition, and Metabolism 45, no. 3 (March 2020): 283–93. http://dx.doi.org/10.1139/apnm-2019-0208.
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Healthy mitochondrial networks are maintained via balanced integration of mitochondrial quality control processes (biogenesis, fusion, fission, and mitophagy). The purpose of this study was to investigate the effects of severe obesity and type 2 diabetes (T2D) on mitochondrial network morphology and expression of proteins regulating mitochondrial quality control processes in cultured human myotubes. Primary human skeletal muscle cells were isolated from biopsies from lean, severely obese nondiabetic individuals and severely obese type 2 diabetic individuals (n = 8–9/group) and were differentiated to myotubes. Mitochondrial network morphology was determined in live cells via confocal microscopy and protein markers of mitochondrial quality control were measured by immunoblotting. Myotubes from severely obese nondiabetic and type 2 diabetic humans exhibited fragmented mitochondrial networks (P < 0.05). Mitochondrial fission protein Drp1 (Ser616) phosphorylation was higher in myotubes from severely obese nondiabetic humans when compared with the lean controls (P < 0.05), while mitophagy protein Parkin expression was lower in myotubes from severely obese individuals with T2D in comparison to the other groups (P < 0.05). These data suggest that regulatory proteins in mitochondrial quality control processes, specifically mitochondrial fission protein Drp1 (Ser616) phosphorylation and mitophagy protein Parkin, are intrinsically dysregulated at cellular level in skeletal muscle from severely obese nondiabetic and type 2 diabetic humans, respectively. These differentially expressed mitochondrial quality control proteins may play a role in mitochondrial fragmentation evident in skeletal muscle from severely obese and type 2 diabetic humans. Novelty Mitochondrial network morphology and mitochondrial quality control proteins are intrinsically dysregulated in skeletal muscle cells from severely obese humans with or without T2D.
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Garza, M. Carmen, Sang-Gyun Kang, Chiye Kim, Eva Monleón, Jacques van der van der Merwe, David A. Kramer, Richard Fahlman, et al. "In Vitro and In Vivo Evidence towards Fibronectin’s Protective Effects against Prion Infection." International Journal of Molecular Sciences 24, no. 24 (December 15, 2023): 17525. http://dx.doi.org/10.3390/ijms242417525.
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A distinctive signature of the prion diseases is the accumulation of the pathogenic isoform of the prion protein, PrPSc, in the central nervous system of prion-affected humans and animals. PrPSc is also found in peripheral tissues, raising concerns about the potential transmission of pathogenic prions through human food supplies and posing a significant risk to public health. Although muscle tissues are considered to contain levels of low prion infectivity, it has been shown that myotubes in culture efficiently propagate PrPSc. Given the high consumption of muscle tissue, it is important to understand what factors could influence the establishment of a prion infection in muscle tissue. Here we used in vitro myotube cultures, differentiated from the C2C12 myoblast cell line (dC2C12), to identify factors affecting prion replication. A range of experimental conditions revealed that PrPSc is tightly associated with proteins found in the systemic extracellular matrix, mostly fibronectin (FN). The interaction of PrPSc with FN decreased prion infectivity, as determined by standard scrapie cell assay. Interestingly, the prion-resistant reserve cells in dC2C12 cultures displayed a FN-rich extracellular matrix while the prion-susceptible myotubes expressed FN at a low level. In agreement with the in vitro results, immunohistopathological analyses of tissues from sheep infected with natural scrapie demonstrated a prion susceptibility phenotype linked to an extracellular matrix with undetectable levels of FN. Conversely, PrPSc deposits were not observed in tissues expressing FN. These data indicate that extracellular FN may act as a natural barrier against prion replication and that the extracellular matrix composition may be a crucial feature determining prion tropism in different tissues.
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Gallagher, Harrison, Hanzla Naeem, Nathanael Wood, Hélène N. Daou, Marcelo G. Pereira, Peter V. Giannoudis, Lee D. Roberts, Anthony Howard, and T. Scott Bowen. "LOCAL AND SYSTEMIC MEDIATORS OF SKELETAL MUSCLE WASTING IN HUMANS FOLLOWING ACUTE TRAUMA." Orthopaedic Proceedings 105-B, SUPP_16 (November 17, 2023): 18. http://dx.doi.org/10.1302/1358-992x.2023.16.018.
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AbstractIntroductionSkeletal muscle wasting is an important clinical issue following acute traumatic injury, and can delay recovery and cause permanent functional disability particularly in the elderly. However, the fundamental mechanisms involved in trauma-induced muscle wasting remain poorly defined and therapeutic interventions are limited.ObjectivesTo characterise local and systemic mediators of skeletal muscle wasting in elderly patients following acute trauma.MethodsExperiments were approved by a local NHS Research Ethics Committee and all participants provided written informed consent. Vastus lateralis biopsies and serum samples were taken from human male and female patients shortly after acute trauma injury in lower limbs (n=6; mean age 78.7±4.4 y) and compared to age-matched controls (n=6; mean age 72.6±6.3 y). Atrogenes and upstream regulators (MuRF1; MAFbx; IL6, TNFα, PGC-1α) mRNA expression was assessed in muscle samples via RT-qPCR. Serum profiling of inflammatory markers (e.g. IL6, TNFα, IL1β) was further performed via multiplex assays. To determine whether systemic factors induced by trauma directly affect muscle phenotype, differentiated primary human myotubes were treated in vitro with serum from controls or trauma patients (pooled; n=3 each) in the final 24 hours of differentiation. Cells were then fixed, stained for myogenin and imaged to determine minimum ferret diameter. Statistical significance was determined at P<0.05.ResultsThere was an increase in skeletal muscle mRNA expression for E3 ligase MAFbx and inflammatory cytokine IL-6 (4.6 and 21.5-fold respectively; P<0.05) in trauma patients compared to controls. Expression of myogenic determination factor MyoD and regulator of mitochondrial biogenesis PGC-1α was lower in muscle of trauma patients vs controls (0.5 and 0.39-fold respectively; P<0.05). In serum, trauma patients showed increased concentrations of circulating pro-inflammatory cytokines IL-6 (14.5 vs. 0.3 pg/ml; P<0.05) and IL-16 (182.7 vs. 85.2 pg/ml; P<0.05) compared to controls. Primary myotube experiments revealed serum from trauma patients induced atrophy (32% decrease in diameter) compared to control serum-treated cells (P<0.001).ConclusionSkeletal muscle from patients following acute trauma injury showed greater expression of atrophy and inflammatory markers. Trauma patient serum exhibited higher circulating pro-inflammatory cytokine concentrations. Primary human myotubes treated with serum from trauma patients showed significant atrophy compared to healthy serum-treated controls. We speculate a mechanism(s) acting via circulating factors may contribute to skeletal muscle pathology following acute trauma.Declaration of Interest(b) declare that there is no conflict of interest that could be perceived as prejudicing the impartiality of the research reported:I declare that there is no conflict of interest that could be perceived as prejudicing the impartiality of the research project.
Dissertations / Theses on the topic "Myotubes humains"
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Jacquemin, Virginie. "Mécanismes cellulaires et moléculaires impliqués dans l'hypertrophie des myotubes humains induite par l'IGF-1." Paris 7, 2006. http://www.theses.fr/2006PA077195.
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L'IGF-1 (Insulin-like Growth factor 1) est un facteur de croissance sécrété par le foie, mais aussi exprimé localement au niveau du muscle où il joue un rôle majeur dans la régulation de la masse. Ainsi, surexprimé au niveau du muscle de souris, l'IGF-1 est capable d'induire une hypertrophie des fibres musculaires et de limiter la perte de masse musculaire liée à l'âge. Dans cette étude, réalisée sur modèle de myoblastes primaires humains, la capacité de l'IGF-1 à induire une hypertrophie des myotubes a pu être retrouvée. En traitant les cultures par l'IGF-1 après 3 jours de différenciation, nous avons développé un modèle d'hypertrophie des myotubes humains indépendant de toute induction de prolifération, et caractérisé par une augmentation de l'index de fusion, résultant du recrutement accru des cellules « de réserve » pour la différenciation et la fusion. Dans ce modèle, nous montrons que l'IGF-1 active les voies Akt et p42MAPK au niveau des myotubes mais pas des cellules réserve, suggérant l'existence d'un second signal émis par les myotubes et aboutissant au recrutement des cellules réserve pour la fusion. Des expériences de milieu conditionné ont permis de montrer que ce second signal était un facteur soluble, sécrété par les myotubes en réponse au traitement par l'IGF-1, et responsable du recrutement des cellules réserve. Grâce à l'utilisation d'anticorps neutralisant, confirmé par un traitement exogène, j'ai montré que l'interleukine 13, dont l'expression est stimulée dans les myotubes par le facteur de transcription NFATc2 en réponse à l'IGF-1, était responsable du recrutement des cellules réserve pour la fusion au cours de l'hypertrophie induite par l'IGF-1 chez l'hommeIGF-1 (Insulin-like Growth factor 1) is a growth factor secreted by the liver in response to GH, but also expressed locally in muscle where it plays a key role in the control of muscle mass. Overexpressed in the muscle of mice, IGF-1 induces muscle hypertrophy and prevents the loss of muscle mass that occurs with aging. In the present study, the ability of IGF-1 to induce myotube hypertrophy has been confirmed in a model of primary human myoblasts. By treating cultures with IGF-1 after 3 days of differentiation, we developed a model of human myotube hypertrophy independent of cell proliferation and charaterized by an increase in fusion index, resulting from the increased recruitment of reserve cells for differentiation and fusion. Using this model, we show that IGF-1 exclusively signals on myotubes but not on reserve cells, suggesting the existence of a secondary mechanism triggered by the myotubes inducing reserve cell recruitment for fusion. Using conditioned medium we observed that a soluble factor secreted by myotubes is responsible for this increase in reserve cell recruitment for fusion in response to IGF-1. This factor was identified as Interleukin-13 using a neutralizing antibody and exogenous treatment. We demonstrate that the expression of IL-13 is induced via the transcription factor NFATcl in response to IGF-1, and is responsible for the increased recruitment of reserve cells for fusion during human myotube hypertrophy induced by IGF-1
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Boyer, Christian. "Identification et caractérisation de composés circulants d’intérêt dans le sérum d’ours brun hibernant – Étude des effets biologiques du sérum d’ours hibernant sur cellules humaines." Electronic Thesis or Diss., Université Clermont Auvergne (2021-...), 2023. http://www.theses.fr/2023UCFA0012.
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L’atrophie musculaire, qui constitue un enjeu majeur en matière de santé publique, est une affection qui touche les personnes âgées, mais aussi les personnes sédentaires, immobilisées ou souffrant d’une inflammation chronique. L’utilisation de modèles animaux, en particulier les rongeurs de laboratoire, a permis d’élucider les mécanismes moléculaires et physiopathologiques à l’origine de l’atrophie musculaire. Dans la recherche de solutions thérapeutiques, l’exploration d’un modèle de résistance naturelle à l’atrophie musculaire doit permettre d’ouvrir de nouvelles pistes de recherche innovantes. Le laboratoire explore comment l‘ours brun hibernant est capable de préserver son tissu musculaire durant plusieurs mois d’immobilité, et comment son sérum est capable d’induire des modifications de la balance protéique sur des cellules musculaires humaines. L’objectif principal de mon travail de thèse était d’identifier des composés ou familles de composés circulants chez l’ours en hibernation, et responsables d’effets biologiques sur des cellules humaines. Dans un premier temps j’ai recherché une activité biologique facilement mesurable, et qui pourrait être utilisée pour cribler les composés circulants. La mesure de l’activité NADH déshydrogénase par un test colorimétrique, permet de suivre les effets inhibiteurs du sérum et de ses fractions sur des cellules humaines en culture, de façon robuste et reproductible. Grace à cet outil, nous avons pu initier le criblage de plusieurs fractions issues du sérum d’ours hibernant, débutant ainsi une approche sans a priori dans la recherche des composés actifs du sérum d’ours hibernant. Ces travaux ouvrent la voie aux tests de nouvelles fractions, permettant d’avancer vers l’identification de nouvelles molécules ayant un effet positif sur la balance énergétique cellulaire. Selon la même démarche, le développement de plusieurs outils de mesure couvrant d’autres domaines du métabolisme cellulaire devrait permettre à l’avenir de compléter cette approche. En parallèle, dans la recherche de composés circulants actifs présent dans le sérum d’ours hibernant, j’ai axé mes recherches sur des composés en relation avec le système endocannabinoïde. J’ai pu ainsi mettre en évidence une diminution globale du tonus endocannabinoïde, avec une diminution des ligands de la voie canonique. De façon surprenante, la concentration d’oleoylethanolamide (OEA) circulante est multipliée par trois en hiver, suggérant un rôle important de ce composé dans la physiologie de l’hibernation chez l’ours brun. La poursuite de ces travaux doit permettre de mieux cerner les composés circulants d’intérêt pour la médecine humaine, et d’avancer vers des solutions thérapeutiques innovantes dans la lutte de certaines pathologies, comme l’atrophie musculaireMuscle atrophy, which is a major public health issue, is a condition that affects the elderly, but also people who are sedentary, immobilized or suffering from chronic inflammation. The use of animal models, in particular laboratory rodents, has made it possible to elucidate the molecular and physiopathological mechanisms at the origin of muscle atrophy. In the search for therapeutic solutions, the exploration of a model of natural resistance to muscle atrophy should open up new and innovative avenues of research. The laboratory is exploring how the hibernating brown bear is able to preserve its muscle tissue during several months of immobility, and how its serum is able to induce changes in the protein balance of human muscle cells. The main objective of my thesis work was to identify compounds or families of compounds circulating in the hibernating bear and responsible for biological effects on human cells. First, I looked for a biological activity that could be easily measured and that could be used to screen the circulating compounds. The measurement of NADH dehydrogenase activity by a colorimetric assay, allows to follow the inhibitory effects of serum and its fractions on human cells in culture, in a robust and reproducible way. Thanks to this tool, we were able to initiate the screening of several fractions from hibernating bear serum, thus starting an unbiased approach in the search for active compounds in hibernating bear serum. This work opens the way to the testing of new fractions, allowing to advance towards the identification of new molecules having a positive effect on the cellular energy balance. According to the same approach, the development of several measurement tools covering other domains of cellular metabolism should allow to complete this approach in the future. In parallel, in the search for active circulating compounds present in the serum of hibernating bears, I focused my research on compounds related to the endocannabinoid system. I was thus able to highlight a global decrease of the endocannabinoid tone, with a decrease of the ligands of the canonical pathway. Surprisingly, the concentration of circulating oleoylethanolamide (OEA) is multiplied by three in winter, suggesting an important role of this compound in the physiology of hibernation in brown bears. The continuation of this work should allow to better identify circulating compounds of interest for human medicine, and to advance towards innovative therapeutic solutions in the fight against certain pathologies, such as muscle atrophy
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YANG, XIAO YAN. "Effets de l'endotheline sur le calcium libre cytosolique et sur l'entree de glucose dans les myoblastes squelettiques humains en culture et dans les myotubes l6 : interet pour la comprehension de l'insuline-resistance." Paris 6, 1995. http://www.theses.fr/1995PA066779.
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Nous avons utilise l'endotheline comme outil pour approfondir le concept selon lequel certains agents vasoactifs, agissant par l'intermediaire de la mobilisation du ca#2#+ et de la stimulation de la proteine kinase c, peuvent agir sur les muscles squelettiques tissus-cibles de la resistance a l'insuline dans hypertension essentielle et modifier le transport du glucose dans ces cellules. D'une part, nous avons montre que les deux modeles choisis -les myoblastes squelettiques humains en culture provenant du vastus lateralis et les myotubes l6, une lignee de cellules musculaires squelettiques de rat- presentent deux sous-classes de recepteurs a l'endotheline, le type eta et le type etb. Le type eta est le recepteur predominant dans les cellules l6. Exposees a cette hormone, nos cellules subissent une tres forte augmentation du calcium libre cytosolique. Cet effet resulte de la mobilisation du ca#2#+ provenant des organelles intracellulaires. D'autre part, nous avons detecte, dans les myoblastes squelettiques humains en culture, l'expression des deux isotypes du transporteur de glucose: le glut-1 present dans la plupart des tissus, et le glut-4 exprime dans les tissus sensibles a l'insuline. Apres avoir verifie que l'insuline augmente l'entree de #3h-deoxy-d-glucose dans nos cellules, le resultat le plus interessant de notre etude est que l'endotheline est egalement capable de stimuler cette entree. L'effet de ce dernier sur l'entree de #3h-deoxy-glucose n'est pas additif a celui de l'insuline. De plus, l'entree de #3h-deoxy-glucose peut etre augmentee par un traitement avec du 12-myristate 13-acetate phorbol, un activateur de la proteine kinase c. L'augmentation de l'entree de #3h-deoxy-d-glucose mediee par l'endotheline et l'insuline est totalement abolie par la calphostine c, un inhibiteur specifique de la proteine kinase c. Ceci suggere que l'augmentation de l'entree de glucose sous l'effet de l'endotheline et de l'insuline, dans les muscles squelettiques humains, fait intervenir des mecanismes dependant, au moins partiellement, de la proteine kinase c. L'angiotensine ii presente un effet similaire a celui de l'endotheline sur le profil du calcium libre cytosolique, mais cet agent est incapable de modifier l'entree de 2-deoxy-d-glucose. Il est donc tres probable que l'alteration du metabolisme du glucose induit par l'endotheline n'est pas liee directement a l'augmentation du calcium cytosolique. En conclusion, des conditions associees a l'augmentation des niveaux d'endotheline ou d'agents similaires a proximite des muscles squelettiques pourraient modifier la reponse de ce tissu a l'insuline. Par consequent, des niveaux augmentes d'endotheline dans le lit vasculaire pourraient contribuer a alterer le metabolisme du glucose dans l'hypertension essentielle, via les muscles squelettiques, et par la meme expliquer pourquoi certains patients hypertendus presentent une diminution de la sensibilite a l'insuline
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Vianello, Sara. "N-Butyryl arginine and 3-Hydroxybutyrate arginine, for the treatment of DMD through oral administration." Thesis, Paris 11, 2013. http://www.theses.fr/2013PA11T046/document.
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La dystrophie musculaire de Duchenne est une maladie neuromusculaire qui touche 1 enfant sur 3500, liée au chromosome X, caractérisée par l’absence de dystrophine, protéine située sous le sarcolemme qui confère stabilité à la membrane cellulaire en connectant l’actine du cytosquelette avec la matrice extracellulaire. Elle fait partie d’un complexe multi protéique, nommé « dystrophin associated protein complex (DAPC)», qui contient, entre autre, le -dystroglycane et l’oxyde nitrique synthase (NOS). Son absence cause la dérégulation de l’homéostasie calcique, la nécrose tissulaire, l’accumulation de tissu graisseux et fibreux, l’incapacité de mouvement et des déficits cardiaques et respiratoires qui aboutissent au décès des patients. Mon travail avait comme objectif l’amélioration de différents aspects du phénotype dystrophique. J’ai utilisé des molécules capables d’activer deux voies de signalisations (la voie du NO et l’inhibition des histones deacetylase (HDAC)), connues pour induire l’amélioration du phénotype dystrophique chez la souris mdx, modèle de la maladie. Plus particulièrement, j’ai testé chez la souris, deux mode d’administration du butyrate d’arginine (AB), la drogue de référence car déjà utilisée en clinique sur des jeunes patients pour une autre indication, par gavage et par injection intrapéritonéale. J’ai étudié aussi deux nouvelles molécules dérivées du AB, qui pourraient être administrées par voie orale et être efficace à faible dose : le 3-Hydroxybutyrate arginate (ABE) et le N-butyril arginine (ABA). AB, ABE et ABA ont été testés in vitro sur les myotubes de patients dystrophiques et in vivo sur des souris mdx. L’administration orale du AB a les mêmes effets positifs que l’injection intrapéritonéale chez les souris mdx. Ces résultats démontrent que l’administration par voie orale doit être prise en considération lors des futurs essais cliniques. Dans un deuxième temps, je me suis focalisée sur les défauts cardiaques. Un suivi par échocardiographie mensuelle a été réalisé sur des souris de 8 mois traitées avec du AB. En parallèle nous avons analysé les effets de l’administration par voie orale du AB sur les déformations de la colonne vertébrale. Enfin, les altérations des signaux de l’électromyogramme (réalisé avec une méthode non invasive développée en clinique et appliquée pour les animaux) ont été également analysées. L’ensemble des résultats obtenus montre que le AB est capable de préserver l’activité cardiaque, d’empêcher la déformation de la colonne vertébrale et de rétablir les paramètres d’excitabilité axonale mesurés chez les souris traitées.Différentes concentrations des ABE et ABA ont été testé in vivo et observé à des faibles doses les mêmes résultats bénéfiques sur de nombreux paramètres structuraux et fonctionnels, que ceux obtenu avec une dose importante de AB (800mg/kg/j). Les deux nouvelles drogues peuvent être administrées à une dose 10 fois inferieur que la dose de AB pour obtenir les mêmes effets. J’ai testé aussi in vitro, sur des cellules musculaires humaines, la capacité des deux produits à induire une augmentation des niveaux intracellulaires d’utrophine et des protéines associées (β-dystroglycan et la myosine embryonnaire). J’ai aussi démontré qu’une augmentation de l’expression de l’utrophine et des protéines associées pouvait être induite par les inhibiteurs d’HDAC (le butyrate, la trichostatine A, l’acide valproique et l’isobutyramide). Enfin, une étude portant sur l’homéostasie calcique a été réalisé car des altérations de cet équilibre sont en partie responsables de la nécrose/dégénérescence du tissue musculaire. En particulier, l’activité spontanée du Ca2+, enregistrée sur le myotubes humaine, été fortement réduite après un traitement agissant sur la voie d’activation du NO et/ou par des inhibiteurs des HDAC. L’ensemble des résultats obtenus apportent la preuve des effets bénéfiques du AB et de ses dérivés sur la DMD, a travers la voie du NO et en inhibant les HDACDuchenne muscular dystrophy is a X-linked progressive neuromuscular disease affecting 1:3500 boys at birth. It is caused by the absence of dystrophin, a subsarcolemmal protein that confers membrane stability linking cytoskeletal actin to the extracellular matrix. It is part of a multi-protein complex called dystrophin associated protein complex (DAPC), which contains, among the other components, -dystroglycan and nitric oxide synthase (NOS).The consequences of the absence of dystrophin are: deregulation of calcium homeostasis, tissues necrosis, progressive accumulation of fat and fibrosis, inability of the movements and cardiac and respiratory failures that lead to patient’s death, around the age of 20-30 years.The objective of my PhD work is to ameliorate different aspects of dystrophic phenotype. In particular I have tested two different ways of administration of arginine butyrate (AB), the reference drug, through feeding-force and intraperitoneal injection. Meanwhile I have studied two new pharmacological molecules, AB derived, which could be administered orally to DMD patients. These compounds are: 3-Hydroxybutyrate arginate (refer as ABE) and N-butyryl arginine (refer as ABA). All of these molecules partially restore dystrophic phenotype activating two independent pathways (both the nitric oxide pathway and the inhibition of the histone deacetilase), which are known to be beneficent for mdx mice.AB, ABE and ABA have been tested in vitro on human DMD myotubes and in vivo on the mdx mice. The first goal of my project is the observation that the positive effects obtained after intraperitoneal injections of AB can be detected also after oral protocol, promoting the idea that the oral way has to be developed for future clinical trials. I have focused my attention on heart defaults; in particular, starting from the 8th month, a monthly study on heart activity based on echocardiography has been performed on mdx mice treated with AB. We addressed the potential profits of the oral administration of arginine butyrate on vertebral column deformation and electromyogram defaults, with a non-invasive automatized method developed in clinic and then applied to animals. The results collected from these experiments show that AB preserve heart activity, reverse vertebral column deformity and all the axonal excitability parameters that were modified in saline-treated mdx mice.In complement, I have tested different concentrations of ABE and ABA in vivo. The positive effects on many structural and functional dystrophic parameters, previously obtained with high dose of AB administered per os (800 mg/kg/d), has been observed with doses 10 times lower with both new compounds.In parallel, both products were tested in vitro on human muscular cells cultures to investigate their capacity to increase utrophin level. Moreover, the potential ability of histone deacetylase inhibitors (byturate, valproic acid, trichostatin A and isobutyramide) to increase the expression of utrophin and related proteins (-dystroglycan and embryonic myosin) has been studied. Finally, the alteration of calcium homeostasis, largely implicated in the cascades resulting in muscle necrosis/degeneration, was investigated. The spontaneous Ca2+ activity recorded in patient myotubes, i.e. without sarcolemmal integrity was strongly reduced after treatment acting on the NO-pathway activation and/or with HDAC inhibitors. All together, these data constitute a proof of principle of the beneficial effects of arginine butyrate and its derivates on muscular dystrophy, by enhancing NO pathway and inhibiting HDAC
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Kanaan, Georges. "Mitochondrial Dysfunction: From Mouse Myotubes to Human Cardiomyocytes." Thesis, Université d'Ottawa / University of Ottawa, 2018. http://hdl.handle.net/10393/37582.
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Mitochondrial dysfunction is a common feature in a wide range of disorders and diseases from obesity, diabetes, cancer to cardiovascular diseases. The overall goal of my doctoral research has been to investigate mitochondrial metabolic dysfunction in skeletal and cardiac muscles in the context of chronic disease development.
Perinatal nutrition is well known to affect risk for insulin resistance, obesity, and cardiovascular disease during adulthood. The underlying mechanisms however, are poorly understood. Previous research from our lab showed that the in utero maternal undernutrition mouse model is one in which skeletal and cardiac muscle physiology and metabolism is impaired. Here we used this model to study the impact of in utero undernutrition on offspring skeletal primary muscle cells and to determine if there is a cell autonomous phenotype. Metabolic analyses using extracellular flux technologies revealed a shift from oxidative to glycolytic metabolism in primary myotubes. Gene expression profiling identified significant changes in mRNA expression, including an upregulation of cell stress and OXPHOS genes and a downregulation of cell division genes. However, there were no changes in levels of marker proteins for mitochondrial oxidative phosphorylation (OXPHOS). Findings are consistent with the conclusion that susceptibility to metabolic disease in adulthood can be caused at least in part by muscle defects that are programmed in utero and mediated by impaired mitochondrial function.
In my second project, the effects of the absence of glutaredoxin-2 (Grx2) on redox homeostasis and on mitochondrial dynamics and energetics in cardiac muscle from mice were investigated. Previous work in our lab established that Grx2-deficient mice exhibit fibrotic cardiac hypertrophy, and hypertension, and that complex I of OXPHOS is defective in isolated mitochondria. Here we studied the role of Grx2 in the control of mitochondrial structure and function in intact cells and tissue, as well as the role of GRX2 in human heart disease. We demonstrated that the absence of Grx2 impacts mitochondrial fusion, ultrastructure and energetics in mouse primary cardiomyocytes and cardiac tissue and that provision of the glutathione precursor, N-acetylcysteine (NAC) did not restore glutathione redox or prevent impairments. Furthermore we used data from the human Genotype-Tissue Expression consortium to show that low GRX2 expression is associated with increased fibrosis, hypertrophy, and infarct in the left ventricle. Altogether, our results indicate that GRX2 plays a major role in cardiac mitochondrial structure and function, and protects against left ventricle pathologies in humans.
In my third project, we collaborated with cardiac surgeon, Dr. Calum Redpath, of the Ottawa Heart Institute to study atrial mitochondrial metabolism in atrial fibrillation patients with and without type 2 diabetes (T2DM). T2DM is a major risk factor for atrial fibrillation, but the causes are poorly understood. Atrial appendages from coronary artery bypass graft surgery were collected and analyzed. We showed an impaired complex I respiration in diabetic patients with atrial fibrillation compared to diabetic patients without atrial fibrillation. In addition, and for the first time in atrial fibrillation patients, mitochondrial supercomplexes were studied; results showed no differences in the assembly of the “traditional” complexes but a decrease in the formation of “high oligomeric” complexes. A strong trend for increased protein oxidation was also observed. There were no changes in markers for OXPHOS protein levels. Overall findings reveal novel aspects of mitochondrial dysfunction in atrial fibrillation and diabetes in humans.
Overall, our results reveal that in utero undernutrition affects the programming of skeletal muscle primary cells, thereby increasing susceptibility to metabolic diseases. In addition, we show that GRX2 impacts cardiac mitochondrial dynamics and energetics in both mice and humans. Finally, we show impaired mitochondrial function and supercomplex assembly in humans with atrial fibrillation and T2DM. Ultimately, understanding the mechanisms causing mitochondrial dysfunction in muscle tissues during chronic disease development will increase our capacity to identify effective prevention and treatment strategies.
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Sishi, Balindiwe J. N. "An investigation into the P13-K/AKT signalling pathway in TNF-a-induced muscle proeolysis in L6 myotubes." Thesis, Stellenbosch : Stellenbosch University, 2008. http://hdl.handle.net/10019.1/3039.
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Thesis (MSc (Physiological Sciences))--Stellenbosch University, 2008.Introduction: Skeletal muscle atrophy is a mitigating complication that is characterized by a reduction in muscle fibre cross-sectional area as well as protein content, reduced force, elevated fatigability and insulin resistance. It seems to be a highly ordered and regulated process and signs of this condition are often seen in inflammatory conditions such as cancer, AIDS, diabetes and chronic heart failure (CHF). It has long been understood that an imbalance between protein degradation (increase) and protein synthesis (decrease) both contribute to the overall loss of muscle protein. Although the triggers that cause atrophy are different, the loss of muscle mass in each case involves a common phenomenon that induces muscle proteolysis. It is becoming evident that interactions among known proteolytic systems (ubiquitin-proteosome) are actively involved in muscle proteolysis during atrophy. Factors such as TNF-α and ROS are elevated in a wide variety of chronic inflammatory diseases in which skeletal muscle proteolysis presents a lethal threat. There is an increasing body of evidence that implies TNF-α may play a critical role in skeletal muscle atrophy in a number of clinical settings but the mechanisms mediating its effects are not completely understood. It is also now apparent that the transcription factor NF-κB is a key intracellular signal transducer in muscle catabolic conditions. This study investigated the various proposed signalling pathways that are modulated by increasing levels of TNF-α in a skeletal muscle cell line, in order to synthesize our current understanding of the molecular regulation of muscle atrophy. Materials and Methods: L6 (rat skeletal muscle) cells were cultured under standard conditions where after reaching ± 60-65% confluency levels, differentiation was induced for a maximum of 8 days. During the last 2 days, myotubes were incubated with increasing concentrations of recombinant TNF-α (1, 3, 6 and 10 ng/ml) for a period of 40 minutes, 24 and 48 hours. The effects of TNF-α on proliferation and cell viability were measured by MTT assay and Trypan Blue exclusion technique. Morphological assessment of cell death was conducted using the Hoechst 33342 and Propidium Iodide staining method. Detection of apoptosis was assessed by DNA isolation and fragmentation assay. The HE stain was used for the measurement of cell size. In order to determine the source and amount of ROS production, MitoTracker Red CM-H2 X ROS was utilised. Ubiquitin expression was assessed by immunohistochemistry. PI3-K activity was calculated by using an ELISA assay and the expression of signalling proteins was analysed by Western Blotting using phospho-specific and total antibodies. Additionally, the antioxidant Oxiprovin was used to investigate the quantity of ROS production in TNF-α-induced muscle atrophy. Results and Discussion: Incubation of L6 myotubes with increasing concentrations of recombinant TNF-α revealed that the lower concentrations of TNF-α used were not toxic to the cells but data analysis of cell death showed that 10 ng/ml TNF-α induced apoptosis and necrosis. Long-term treatment with TNF-α resulted in an increase in the upregulation of TNF- α receptors, specifically TNF-R1. The transcription factors NF-κB and FKHR were rapidly activated thus resulting in the induction of the ubiquitin-proteosome pathway. Activation of this pathway produced significant increases in the expression of E3 ubiquitin ligases MuRF-1 and MAFbx. Muscle fibre diameter appeared to have decreased with increasing TNF-α concentrations in part due to the suppressed activity of the PI3-K/Akt pathway as well as significant reductions in differentiation markers. Western blot analysis also showed that certain MAPKs are activated in response to TNF-α. No profound changes were observed with ROS production. Finally, the use Oxiprovin significantly lowered cell viability and ROS production. These findings suggest that TNF-α may elicit strong catabolic effects on L6 myotubes in a dose and time dependent manner. Conclusion: These observations suggest that TNF-α might have beneficial effects in skeletal muscle in certain circumstances. This beneficial effect however is limited by several aspects which include the concentration of TNF-α, cell type, time of exposure, culture conditions, state of the cell (disturbed or normal) and the cells stage of differentiation. The effect of TNF-α can be positive or negative depending on the concentration and time points analysed. This action is mediated by various signal transduction pathways that are thought to cooperate with each other. More understanding of these pathways as well as their subsequent upstream and downstream constituents is obligatory to clarify the central mechanism/s that control physiological and pathophysiological effects of TNF-α in skeletal muscle.
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Loro, Emanuele Loro. "Normal myogenesis and increased apoptosis in myotonic dystrophy type-1 muscle cells." Doctoral thesis, Università degli studi di Padova, 2010. http://hdl.handle.net/11577/3423200.
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Myotonic dystrophy type 1 (DM1) is caused by (CTG)n expansion in the 3’-untranslated region of DMPK gene. Mutant transcripts are retained in nuclear RNA foci, which sequester RNA binding proteins thereby misregulating their functions (i.e. splicing regulation). Controversy still surrounds the pathogenesis of the DM1 muscle distress, characterized by myotonia, weakness and wasting with distal muscle atrophy.
Eight primary human cell lines from adult-onset (DM1) and congenital (cDM1) patients, (CTG)n range 90-1800, were successfully differentiated into aneural-immature and contracting-innervated-mature myotubes. Morphological, immunohistochemical, RT-PCR and Western blotting analyses of several markers of myogenesis indicated that in vitro differentiation-maturation of DM1 myotubes was comparable to age-matched controls. In all pathological muscle cells, (CTG)n expansions were confirmed by long PCR and RNA fluorescence in-situ hybridization. Moreover, the DM1 myotubes displayed the splicing alteration of insulin receptor and MBNL1 genes associated to the DM1 phenotype.
Considerable myotube loss and atrophy of 15-day-differentiated DM1 myotubes indicated activated catabolic pathways, as confirmed by the presence of apoptotic (caspase-3 activation, cytochrome c release, chromatin fragmentation) and autophagic (P62/LC3) markers. Treatment with the pancaspase inhibitor Z-VAD significantly reduced the decrease in myonuclei number and in average width in15-day-differentiated DM1 myotubes. We thus propose that the muscle wasting typical in DM1 is due to impairment of muscle mass maintenance-regeneration, through premature apoptotic-autophagic activation, rather than altered myogenesis.La distrofia miotonica di tipo 1 (DM1) è causata dall'espansione (CTG)n nella regione trascritta ma non tradotta al 3' del gene DMPK. I trascritti mutati sono trattenuti in foci nucleari, i quali sequestrano diverse proteine leganti RNA spesso alterandone le funzioni (i.e. regolazione dello splicing). A livello del muscolo, i meccanismi patogenetici che portano a miotonia, debolezza e perdita di massa dei muscoli distali, non sono ad oggi chiari. Otto linee di mioblasti primari umani, ottenuti da biopsie di pazienti affetti da DM1 nelle forme adulta e congenita (range di espansione tra 90 e 1800 CTG), sono state differenziate ed innervate con successo, ottenendo miotubi in grado i contrarre. L'analisi morfologica e la quantificazione di diversi marker di miogenesi mediante RT-PCR e Western blotting, hanno indicato che il diferenziamento in vitro dei mioblasti primari DM1 è indistinguibile da quello ottenuto con mioblasti di controllo. In ciascuna linea DM1 è stata confermata l'espansione (CTG)n mediante long-PCR ed ibridizzazione in situ. Inoltre, nei miotubi DM1 è stato rilevata l'alterazione dello splicing del recettore per l'insulina e di MBNL1, caratteristica del fenotipo DM1. A 15 giorni di differenziamento, una considerevole perdita di miotubi DM1 ha suggerito l'attivazione di pathways catabolici, come confermato dalla presenza di marker di apoptosi (taglio proteolitico della caspasi 3, rilascio di citocromo c dai mitocondri, frammentazione della cromatina) e di autofagia (aumento dei livelli di LC3 lipidato e di P62). Il trattamento con l'inibitore delle caspasi Z-VAD si è dimostrato efficace nell'attenuare la riduzione del numero di mionuclei e del calibro medio dei miotubi a 15 giorni di differenziamento. Proponiamo quindi che la compromissione muscolare tipica della DM1 sia dovuta, più che ad un'alterata miogenesi, a problemi nei meccanismi di mantenimento/rigenerazione, che si esplicano attraverso la prematura attivazione di apoptosi e/o autofagia
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Harisseh, Rania. "Rôle des entrées capacitives et de TRPV2 dans la dérégulation de l'homéostasie calcique dans le muscle squelettique humain : implication dans la dystrophie musculaire de Duchenne." Thesis, Poitiers, 2012. http://www.theses.fr/2012POIT2258/document.
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La dystrophie musculaire de Duchenne (DMD) est la conséquence de la perte de la dystrophine, une protéine cytosquelettique indispensable au maintien mécanique et fonctionnel du sarcolemme. Notre équipe a largement étudié les entrées cationiques dans les lignées murines et a montré : 1- une augmentation anormale des influx dépendant des stocks calciques (SOCE) dans les myotubes (MT) déficients en dystrophine (dys-), 2- que les influx SOCE sont médiés par les canaux TRPC1 et TRPC4, 3- que la dérégulation des SOCE dans les MT dys- est corrigée grâce à la surexpression de l'α1-syntrophine. Au jour d'aujourd’hui, il existe peu d'éléments dans la littérature quant à la caractérisation des entrées SOCEs dans les cellules musculaires humaines et dans la DMD. Ce travail de thèse s'articule autour de deux parties : Le modèle murin, dans lequel nous avons montré un rôle indispensable de STIM1 et Orai1 dans la mise en place des entrées SOCEs et l'implication de la voie Ca2+/PLC/PKC dans l'augmentation anormale de ces entrées dans les MT murins dys-. Le modèle humain primaire, dans lequel nous avons mis en évidence : 1- une augmentation anormale des influx SOCEs dans les MT DMD et établit le profil d'expression des différentes protéines nécessaires à la mise en place de ces entrées ; 2- l'implication de la voie Ca2+/PLC/PKC dans la dérégulation des SOCEs dans les MT humains DMD et le rôle de l'α1-syntrophine dans la régulation de ces entrées dans les MT humains ; 3- la dérégulation de l'homéostasie calcique dans la DMD qui se produit par l'intermédiaire des entrées cationiques dépendantes de TRPV2 dans les cellules musculaires dystrophiquesDuchenne muscular dystrophy (DMD) is the consequence of the loss of dystrophin, a cytoskeletal protein essential for the mechanical and functional maintenance of the sarcolemma. Our group has extensively studied store-operated cation influx (SOCE) in mouse cell lines and highlighted: 1- an abnormal increase in SOCE in dystrophin-deficient (dys-) mouse myotubes (MT), 2- That SOCE are mediated by TRPC1 and TRPC4, 3- that SOCE deregulation in dys- MT is corrected by overexpression of α1-syntrophin. As of today, there is little evidence in the literature regarding the characterization of SOCE in human muscle cells and in human DMD. This thesis work is divided in two parts : In the murine model, we demonstrated an essential role of STIM1 and Orai1 in the establishment of SOCE and highlighted the involvement of Ca2+/PLC/PKC pathway in the abnormal increase of cation entry in dystrophin-deficient mouse myotubes.In primary human model, we showed: 1- an abnormal increase of SOCE in DMD MT and established the expression profile of various proteins necessary for the implementation of this influx; 2- the involvement of Ca2+/PLC/PKC in SOCE deregulation in human DMD MT and the role of α1-syntrophin in the regulation of cation entry in human MT; 3- the deregulation of calcium homeostasis in DMD that occurs through TRPV2. This work proposes a new regulatory pathway, Ca2+/PLC/PKC, for SOCE in skeletal muscle cells and provides the first elements of the disruption of calcium homeostasis in DMD human myotubes due to the absence of SOCE's regulation by the α1-syntrophin and to the overactivation of TRPV2 channels
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Thomas, Mark Peter. "Acute simulated hypoxia and ischemia in cultured C2C12 myotubes : decreased phosphatidylinositol 3-kinase (PI3K)/Akt activity and its consequences for cell survival." Thesis, Stellenbosch : Stellenbosch University, 2008. http://hdl.handle.net/10019.1/2610.
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Thesis (MSc (Physiological Sciences))--Stellenbosch University, 2008.Cells are equipped with an array of adaptive mechanisms to contest the undesirable effects of ischemia and the associated hypoxia. Indeed, many studies have suggested that there is an increase in the PI3K/Akt pathway activation during hypoxia and ischemia. Damaged muscle can be regenerated by recruiting myogenic satellite cells which undergo differentiation and ultimately lead to the regeneration of myofibres. The C2C12 murine myogenic cell line is popular for studying myogenesis in vitro, and has been used in many studies of ischemic microenvironments. PI3K/Akt pathway activity is increased during C2C12 myogenesis and this is known to produce an apoptosis resistant phenotype. In this study, we provide evidence that high basal levels of PI3K activity exist in C2C12 myotubes on day ten post-differentiation. Ischemia is characterized by depleted oxygen and other vital nutrients, and ischemic cell death is believed to be associated with an increasingly harsh environment where pH levels decrease and potassium levels increase. By employing a model that mimics these changes in skeletal muscle culture, we show that both acute simulated ischemia and acute hypoxia cause decreases in endogenous levels of the p85 and p110 subunits of PI3K and a consequent reduction in PI3K activity. Supplementing skeletal muscle cultures with inhibitors of the PI3K pathway provides evidence that the protective effect of PI3K/Akt is subsequently lost in these conditions. Using Western blot analysis, a PI3K ELISA assay as well as known inhibitors of the PI3K pathway in conjunction with the MTT assay we are able to demonstrate that the activation of downstream effectors of PI3K, including Akt, are concurrently decreased during acute simulated ischemia and acute hypoxia in a manner that is independent of PDK-1 and PTEN and that the decreases in the PI3K/Akt pathway activity produce a knock-on effect to the downstream signalling of transcription factors, such as Fox01 and Fox04, in our model. We proceed to provide compelling evidence that the apoptotic resistance of C2C12s is at least partially lost due to these decreases in PI3K/Akt pathway activity, by showing increased caspase-3 and PARP cleavage. Then, using vital staining techniques and a DNA fragmentation assay, we demonstrate increased cell membrane impairment, cell death and apoptosis after three hours of simulated ischemia and hypoxia in cultured C2C12 myotubes. In addition to the main findings, we produce evidence of decreased flux through the mTOR pathway, by showing decreased Akt-dependant phosphorylation at the level of TSC2 and mTOR during simulated ischemia and hypoxia. Finally, we present preliminary findings indicating increased levels of HIF1α and REDD-1, representing a possible oxygen sensing mechanism in our model. Therefore, we show that there is in fact a rapid decrease in PI3K/Akt activity during severe, acute simulated ischemia and hypoxia in C2C12 myotubes on day ten post-differentiation, and this causes a concomitant down regulation in cell survival pathways and increased activity of cell death machinery. Thereafter, we propose a possible mechanism of action and provide a platform for future studies.
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Defour, Aurélia. "Fonctions métaboliques de Sirtuine 1 dans le muscle strié squelettique : contribution à l'étude de la régulation de l'expression de SREBP-1c et rôle potentiel lors d'un jeûne chez des myotubes C2C12." Phd thesis, Université Jean Monnet - Saint-Etienne, 2010. http://tel.archives-ouvertes.fr/tel-00677025.
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Sirt1 (Sirtuine 1) est une protéine histone déacétylase dépendante de NAD+ qui stimule la néoglucogénèse et inhibe la glycolyse dans le foie, et qui augmente l'oxydation des acides gras dans le muscle strié squelettique. Le but de ce travail de thèse a été de définir les fonctions métaboliques de Sirt1 dans le muscle strié squelettique. Nous avons tout d'abord montré, à l'aide d'un modèle de souris déficientes pour le gène Sirt1, que Sirt1 régulait l'expression de l'hexokinase II et de SREBP-1c, protéine régulatrice de l'expression de l'hexokinase. De plus, un modèle d'électrotransfert de gènes permettait de mettre en évidence que Sirt1 régulait l'expression de SREBP-1c de façon LXR dépendante. Enfin, l'inhibition de Sirt1 par l'EX527 aboutissait à une diminution de la consommation de glucose chez des myotubes C2C12. Prises ensemble, ces données suggèrent un rôle important de Sirt1 dans la régulation du métabolisme du glucose dans le muscle strié squelettique. Dans un second temps, nous avons déterminé le rôle potentiel de Sirt1 lors d'un jeûne chez des myotubes C2C12. Un jeûne entraînait une augmentation de l'activité cathepsine B + L et une déphosphorylation des protéines AktS473, GSK3S21/S9, p70S6KT412 et S6 S235/S236 qui précédait une amyotrophie des myotubes. La renutrition aboutissait à une rephosphorylation de ces protéines et à un retour à la normale de la taille des myotubes. L'activité cathepsine B + L restait cependant élevée. Enfin, le niveau en ARNm de Sirt1 était augmenté de façon transitoire lors de la renutrition. D'autres mesures de marqueurs des voies protéolytiques et de l'activité de Sirt1 sont à envisager. Nos données ainsi que celles de la littérature suggèrent que Sirt1 pourrait avoir un rôle dans la régulation de l'autophagie lors du jeûne. Pour conclure, ce travail de thèse met en évidence un rôle pour Sirt1 dans la régulation du métabolisme du glucose dans le muscle strié squelettique et apporte de nouvelles perspectives dans l'étude de la régulation de ce métabolisme en conditions pathologiques
Book chapters on the topic "Myotubes humains"
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Erxleben, Christian, Joachim Ubl, and Hans-Albert Kolb. "Identifying and characterizing stretch-activated ion channels." In Molecular Neurobiology, 75–91. Oxford University PressOxford, 1991. http://dx.doi.org/10.1093/oso/9780199631087.003.0004.
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Abstract The first observation of stretch-activated (SA) channels was probably accidental. It is a common practice to use moderate suction on the tubing connected to the patch-pipette to facilitate the formation of a gigaohm seal. The first reports of SA-channels were those of Guharay and Sachs (1984) (1) on chick myotubes and of Brehm et al. (1984) (2) on embryonic Xenopus muscle. Subsequently, SA-channels have been found in a variety of biological systems, ranging from bacteria, yeast, and plant cells, over molluscan heart muscle to vertebrate oocytes, lens epithelia, endothelial cell lines and kidney cells (for reviews see: refs 3, 4 and 39). The most recent reports also include K+-selective SA-channels in growth cones of neurons, where they co-exist with stretch-inactivated channels (5), in human fibroblasts (6), embryos of fresh-water fish (7) and in stretch-receptor neurons of the crayfish (8, 9).
Conference papers on the topic "Myotubes humains"
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Maurer, Jennifer, Martin Irmler, Johannes Beckers, Andreas L. Birkenfeld, Andreas Peter, and Cora Weigert. "Structural changes in human myotubes lead to impaired human myotube contractility under metformin treatment." In Diabetes Kongress 2023 - 57. Jahrestagung der DDG. Georg Thieme Verlag, 2023. http://dx.doi.org/10.1055/s-0043-1768003.
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Dreher, Simon I., Paul Grubba, Alessia Moruzzi, Christine von Toerne, Thomas Goj, Andreas L. Birkenfeld, Andreas Peter, Stefanie Hauck, Peter Loskill, and Cora Weigert. "Engineering of functionally active human myotubes and myobundles in vitro." In Diabetes Kongress 2023 - 57. Jahrestagung der DDG. Georg Thieme Verlag, 2023. http://dx.doi.org/10.1055/s-0043-1767855.
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Pomiès, Pascal, Matthias Catteau, Marine Blaquière, Farès Gouzi, Jonathan Maury, Bronia Ayoub, Jacques Mercier, and Maurice Hayot. "The COPD plasmatic microenvironment induces atrophy of healthy human myotubes in vitro." In ERS International Congress 2017 abstracts. European Respiratory Society, 2017. http://dx.doi.org/10.1183/1393003.congress-2017.pa2000.
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Catteau, Matthias, Farès Gouzi, Léo Blervaque, Emilie Passerieux, Marine Blaquière, François Bughin, Nelly Héraud, Jacques Mercier, Maurice Hayot, and Pascal Pomiès. "Post-exercise training serum from COPD patients induces atrophy of healthy human myotubes in vitro." In ERS International Congress 2018 abstracts. European Respiratory Society, 2018. http://dx.doi.org/10.1183/13993003.congress-2018.pa4134.
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Catteau, Matthias, Farès Gouzi, Léo Blervaque, Emilie Passerieux, Marine Blaquière, Bronia Ayoub, François Bughin, Jacques Mercier, Maurice Hayot, and Pascal Pomiès. "An in vitro method showing the atrophic effect of the COPD serum on healthy human myotubes." In ERS International Congress 2019 abstracts. European Respiratory Society, 2019. http://dx.doi.org/10.1183/13993003.congress-2019.pa5409.
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Schiele, Nathan R., Douglas B. Chrisey, and David T. Corr. "Proliferation and Fiber Formation of Human Dermal Fibroblasts on Patterned Differentially Adherent Substrates." In ASME 2008 Summer Bioengineering Conference. American Society of Mechanical Engineers, 2008. http://dx.doi.org/10.1115/sbc2008-192910.
Full textAbstract:
Fibroblast cells are crucial in the human body for maintenance of the extracellular matrix, including synthesizing macromolecules like collagen, and they play a critical role in wound healing of soft tissues such as skin [1]. Directing fibroblast growth is an important step in tissue engineering where the focus has gone from a top-down approach of homogeneously introducing cells into a pre-formed scaffold to a bottom-up approach in which the tissue construct is built on a cell-by-cell basis with ability to manipulate specific cell environments through location, proximity, and geometry. The ability to direct cell proliferation to encourage organized tissue formation can provide tissue engineers a means of controlling the architectural and mechanical properties of soft tissue scaffolds. This approach to functional tissue engineering represents a novel direction for the development of replacement tissues. Previous attempts of directed growth have proven successful with C2C12 mouse myoblast cells. Using laser micromachined channels in agarose hydrogel lined with a basement membrane matrix, myoblast cells were guided to align and produce myotubes [2]. The objective of the current study was to apply similar principals to direct fibroblast cell growth and proliferation, ultimately leading to their growth into three-dimensional fibers, on differentially adherent substrates. Channels (widths ranging from 60 μm to 200 μm) were laser micromachined in agarose gel to explore an optimal geometry for cellular proliferation and fiber formation. The fibroblast cells used range in size from roughly 20–30 μm. Thus, the width of each channel was chosen to explore which multiple of cell width would allow for directional alignment parallel to the channel and subsequent fiber growth. The ability to direct fibroblast cells to align and produce fibers through manipulation of their environment is critical to our laboratory’s ongoing efforts to develop three-dimensional customized tissue replacement constructs to be used in many soft tissue applications such as ligament and skin grafts.