Identification de traceurs de l'efficacité d'un traitement: techniques haut débit

Identification de traceurs de l'efficacité d'un traitement: techniques haut débit. Science datin

Étude des voies de signalisation MAPK et PI3K/Akt dans deux modèles animaux de la dystrophie musculaire de Duchenne (la souris mdx et le chien GRMD)

Bien que l origine de la dystrophie musculaire de Duchenne soit connue, des mutations dans le gène DMD aboutissant à l absence de dystrophine, les mécanismes globaux définissant la pathogénie ne sont toujours pas élucidés. L implication d un dérèglement des voies de signalisation a été suggéré et nous souhaitions utiliser la technologie des puces à anticorps pour obtenir une vision globale des modulations affectant les voies MAPK et PI3K/Akt dans le muscle dystrophique. Après une première étude chez la souris mdx, les travaux ont été poursuivis sur le modèle du chien GRMD qui, de part sa physio-pathologie extrêmement proche de celle de l homme, nous paraissait plus adapté. La comparaison du profil de phosphorylation de 19 kinases dans les muscles sain et GRMD révèle que Akt1, ses cibles directes et indirectes GSK3b et p70S6K, ainsi que les MAPK ERK1/2, p38d et p38g présentent toutes une phosphorylation réduite dans le muscle GRMD. Les tests d activité enzymatique montrent que le défaut de phosphorylation des kinases de la voie PI3K/Akt détecté est associé à une activité réduite pour Akt et augmentée pour GSK3b (corrélé par une sur-expression de la kinase). Des expériences de western blot et des tests enzymatiques révèlent une augmentation de l expression et de l activité de la phosphatase PTEN, alors que les expériences de double marquage immunologique montrent la présence dans le muscle GRMD de fibres PTEN/GSK3b-positives et ce, à plusieurs stades. L ensemble de ces travaux suggère que l activation de PTEN dans le muscle dystrophique pourrait empêcher l hypertrophie compensatoire régulée par la voie PI3K/Akt et aggraver les conséquences de l absence de dystrophineAlthough the origin of Duchenne muscular dystrophy is known, mutations in the DMD gene leading to the absence of dystrophin, the global mechanisms defining the pathogenesis are not yet understood. The implication of signaling pathway deregulation has been suggested and we wanted to take advantage of the antibody array technology to obtain a global overview of the modulations affecting the MAPK and PI3K/Akt pathways in dystrophic muscle. After a first study in the mdx mouse model, the work has been carried out in the GRMD dog that, thanks to its pathophysiology extremely close to that of human patients, appeared more pertinent to this study. The comparison of the phosphorylation profile of 19 different kinases between healthy and GRMD skeletal muscles reveale that Akt1, its direct and indirect targets GSK3b and p70S6K, along with the MAPK ERK1/2, p38d and p38g, all exhibit a reduced phosphorylation level in GRMD muscle. Enzymatic assays show that the phosphorylation defect of the PI3K/Akt pathway kinases detected in GRMD muscle is associated with decreased Akt and increased GSK3b activity (corroborated by an over-expression of the kinase). Western immunoblot experiments and enzymatic assays reveal increased expression and activity of the PTEN phosphatase, whereas immunohistochemcal double staining experiments show the presence in GRMD muscle sections of PTEN/GSK3b-positive fibers, and this at different stages of the disease. Taken together, these results suggest that PTEN activation in dystrophic muscle could prevent the compensatory hypertrophy response that is regulated by the PI3K/Akt pathway, and exacerbate the consequences of the absence of dystrophinNANTES-BU Sciences (441092104) / SudocSudocFranceF

Numerical comparison of eigenvalue algorithms for vibroacoustic problems

International audienceThis paper concerns the study of vibroacoustic problems. By considering a displacement-pressure formulation, a non-symmetric eigenvalue problem is obtained. In order to solve it, three numerical schemes are compared: the classical ARPACK solver, an indicator method (initially proposed in B. Claude et al. Comptes Rendus Mécaniques, 2017, 345(2)) which has the property to be null at the eigenvalues, and an original method based on the analysis of Taylor series expansions near a singularity. Numerical results show all the evaluated numerical methods give accurate results but the indicator method requires the lowest computational times. Nevertheless, the original method based on the behavior of the perturbation method close to eigenvalues seems to be a very promising technique

Isolement et caractérisation des vésicules extracellulaires sécrétées par les cellules souches humaines MuStem : rôle potentiel en médecine régénératrice ?

Isolement et caractérisation des vésicules extracellulaires sécrétées par les cellules souches humaines MuStem : rôle potentiel en médecine régénératrice ?. XXXème congrès de l'AFH: les nouveaux mondes de l'histologi

Isolement et caractérisation des vésicules extracellulaires sécrétées par les cellules souches humaines MuStem : rôle potentiel en médecine régénératrice ?

Isolement et caractérisation des vésicules extracellulaires sécrétées par les cellules souches humaines MuStem : rôle potentiel en médecine régénératrice ?. XXXème congrès de l'AFH: les nouveaux mondes de l'histologi

Repair of myocardial infarction with human adult muscle-derived stem cells “MuStem”

Repair of myocardial infarction with human adult muscle-derived stem cells “MuStem”. Congrès du GRRC (Groupe de Reflexion sur la Recherche Cardiovasculaire

Repair of myocardial infarction with human adult muscle-derived stem cells “MuStem”

Repair of myocardial infarction with human adult muscle-derived stem cells “MuStem”. 6eme congrés international de Myologi

Repair of myocardial infarction with human adult muscle-derived stem cells “MuStem”

Repair of myocardial infarction with human adult muscle-derived stem cells “MuStem”. Congrès du GRRC (Groupe de Reflexion sur la Recherche Cardiovasculaire

Differential Gene Expression Profiling of Dystrophic Dog Muscle after MuStem Cell Transplantation.

Several adult stem cell populations exhibit myogenic regenerative potential, thus representing attractive candidates for therapeutic approaches of neuromuscular diseases such as Duchenne Muscular Dystrophy (DMD). We have recently shown that systemic delivery of MuStem cells, skeletal muscle-resident stem cells isolated in healthy dog, generates the remodelling of muscle tissue and gives rise to striking clinical benefits in Golden Retriever Muscular Dystrophy (GRMD) dog. This global effect, which is observed in the clinically relevant DMD animal model, leads us to question here the molecular pathways that are impacted by MuStem cell transplantation. To address this issue, we compare the global gene expression profile between healthy, GRMD and MuStem cell treated GRMD dog muscle, four months after allogenic MuStem cell transplantation.In the dystrophic context of the GRMD dog, disease-related deregulation is observed in the case of 282 genes related to various processes such as inflammatory response, regeneration, calcium ion binding, extracellular matrix organization, metabolism and apoptosis regulation. Importantly, we reveal the impact of MuStem cell transplantation on several molecular and cellular pathways based on a selection of 31 genes displaying signals specifically modulated by the treatment. Concomitant with a diffuse dystrophin expression, a histological remodelling and a stabilization of GRMD dog clinical status, we show that cell delivery is associated with an up-regulation of genes reflecting a sustained enhancement of muscle regeneration. We also identify a decreased mRNA expression of a set of genes having metabolic functions associated with lipid homeostasis and energy. Interestingly, ubiquitin-mediated protein degradation is highly enhanced in GRMD dog muscle after systemic delivery of MuStem cells.Overall, our results provide the first high-throughput characterization of GRMD dog muscle and throw new light on the complex molecular/cellular effects associated with muscle repair and the clinical efficacy of MuStem cell-based therapy

Flow chart of the statistical filtration of microarray data.

<p>Procedure leading to classification for each of the three pairwise comparisons of healthy, GRMD and GRMD^MuStem dog muscle samples.</p