4E-BP1 and 4E-BP2 double knockout mice are protected from aging-associated sarcopenia

Epub ahead of printBACKGROUND: Sarcopenia is the loss of muscle mass/function that occurs during the aging process. The links between mechanistic target of rapamycin (mTOR) activity and muscle development are largely documented, but the role of its downstream targets in the development of sarcopenia is poorly understood. Eukaryotic initiation factor 4E-binding proteins (4E-BPs) are targets of mTOR that repress mRNA translation initiation and are involved in the control of several physiological processes. However, their role in skeletal muscle is still poorly understood. The goal of this study was to assess how loss of 4E-BP1 and 4E-BP2 expression impacts skeletal muscle function and homeostasis in aged mice and to characterize the associated metabolic changes by metabolomic and lipidomic profiling. METHODS: Twenty-four-month-old wild-type and whole body 4E-BP1/4E-BP2 double knockout (DKO) mice were used to measure muscle mass and function. Protein homeostasis was measured ex vivo in extensor digitorum longus by incorporation of l-[U-(14) C]phenylalanine, and metabolomic and lipidomic profiling of skeletal muscle was performed by Metabolon, Inc. RESULTS: The 4E-BP1/2 DKO mice exhibited an increase in muscle mass that was associated with increased grip strength (P < 0.05). Protein synthesis was higher under both basal (+102%, P < 0.05) and stimulated conditions (+65%, P < 0.05) in DKO skeletal muscle. Metabolomic and complex lipid analysis of skeletal muscle revealed robust differences pertaining to amino acid homeostasis, carbohydrate abundance, and certain aspects of lipid metabolism. In particular, levels of most free amino acids were lower within the 4E-BP1/2 DKO muscle. Interestingly, although glucose levels were unchanged, differences were observed in the isobaric compound maltitol/lactitol (33-fold increase, P < 0.01) and in several additional carbohydrate compounds. 4E-BP1/2 depletion also resulted in accumulation of medium-chain acylcarnitines and a 20% lower C2/C0 acylcarnitine ratio (P < 0.01) indicative of reduced beta-oxidation. CONCLUSIONS: Taken together, these findings demonstrate that deletion of 4E-BPs is associated with perturbed energy metabolism in skeletal muscle and could have beneficial effects on skeletal muscle mass and function in aging mice. They also identify 4E-BPs as potential targets for the treatment of sarcopenia

Les endocannabinoïdes stimulent la synthèse protéique dans un modèle de myotubes en culture

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Acute rimonabant treatment promotes protein synthesis in C2C12 myotubes through a CB1‐independent mechanism

International audienceSarcopenia is an age-related loss of muscle mass associated with changes in skeletal muscle protein homeostasis due to lipid accumulation and anabolic resistance; changes that are also commonly described in obesity. Activation of the endocannabinoid system is associated with the development of obesity and insulin resistance, and with the perturbed skeletal muscle development. Taken together this suggests that endocannabinoids could be regulators of skeletal muscle protein homeostasis. Here we report that rimonabant, an antagonist for the CB1 receptor, can prevent dexamethasone-induced C2C12 myotube atrophy without affecting the mRNA expression of atrogin-1/MAFbx (a marker of proteolysis), which suggests it is involved in the control of protein synthesis. Rimonabant alone stimulates protein synthesis in a time- and dose-dependent manner through mTOR- and intracellular calcium-dependent mechanisms. CB1 agonists are unable to modulate protein synthesis or prevent the effect of rimonabant. Using C2C12 cells stably expressing an shRNA directed against CB1, or HEK293 cells overexpressing HA-tagged CB1, we demonstrated that the effect of rimonabant is unaffected by CB1 expression level. In summary, rimonabant can stimulate protein synthesis in C2C12 myotubes through a CB1-independent mechanism. These results highlight the need to identify non-CB1 receptor(s) mediating the pro-anabolic effect of rimonabant as potential targets for the treatment of sarcopenia, and to design new side-effect-free molecules that consolidate the effect of rimonabant on skeletal muscle protein synthesis

L’activité BCATm n’est pas modifiée dans l’intestin, mais augmenté dans le muscle chez le rat âgé

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Impact of enriched environment on tumor growth and adipokines secretion in a mouse model of mammary cancer

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Cellular Expression of Cyclooxygenase, Aromatase, Adipokines, Inflammation and Cell Proliferation Markers in Breast Cancer Specimen

Current evidences suggest that expression of Ki67, cyclooxygenase (COX), aromatase, adipokines, prostaglandins, free radicals, beta-catenin and alpha-SMA might be involved in breast cancer pathogenesis. The main objective of this study was to compare expression/localization of these potential compounds in breast cancer tissues with tissues collected adjacent to the tumor using immunohistochemistry and correlated with clinical pathology. The breast cancer specimens were collected from 30 women aged between 49 and 89 years who underwent breast surgery following cancer diagnosis. Expression levels of molecules by different stainings were graded as a score on a scale based upon staining intensity and proportion of positive cells/area or individually. AdipoR1, adiponectin, Ob-R, leptin, COX-1, COX-2, aromatase, PGF(2a), F-2-isoprostanes and alpha-SMA were localised on higher levels in the breast tissues adjacent to the tumor compared to tumor specimens when considering either score or staining area whereas COX-2 and AdipoR2 were found to be higher considering staining intensity and Ki67 on score level in the tumor tissue. There was no significant difference observed on beta-catenin either on score nor on staining area and intensity between tissues adjacent to the tumor and tumor tissues. A positive correlation was found between COX-1 and COX-2 in the tumor tissues. In conclusion, these suggest that Ki67, COXs, aromatase, prostaglandin, free radicals, adipokines, beta-catenin and alpha-SMA are involved in breast cancer. These further focus the need of examination of tissues adjacent to tumor, tumor itself and compare them with normal or benign breast tissues for a better understanding of breast cancer pathology and future evaluation of therapeutic benefit

Suicide plus immune gene therapy prevents post-surgical local relapse and increases overall survival in an aggressive mouse melanoma setting

In an aggressive B16-F10 murine melanoma model, we evaluated the effectiveness and antitumor mechanisms triggered by a surgery adjuvant treatment that combined a local suicide gene therapy (SG) with a subcutaneous genetic vaccine (Vx) composed by B16-F10 cell extracts and lipoplexes carrying the genes of human interleukin-2 and murine granulocyte and macrophage colony stimulating factor. Pre-surgical SG treatment, neither alone nor combined with Vx was able to slow down the fast evolution of this tumor. After surgery, both SG and SG+Vx treatments, significantly prevented (in 50 % of mice) or delayed (in the remaining 50 %) post-surgical recurrence, as well as significantly prolonged recurrence-free (SG and SG+Vx) and overall median survival (SG+Vx). The treatment induced the generation of a pseudocapsule wrapping and separating the tumor from surrounding host tissue. Both, SG and the subcutaneous Vx, induced this envelope that was absent in the control group. On the other hand, PET scan imaging of SG+Vx group suggested the development of an effective systemic immunostimulation that enhanced 18FDG accrual in thymus, spleen and vertebral column. When combined to surgery, direct intralesional injection of suicide gene plus distal subcutaneous genetic vaccine displayed efficacy and systemic antitumor immune response without host toxicity. This suggests the potential value of the assayed approach for clinical purposes.Fil: Villaverde, Marcela Solange. Universidad de Buenos Aires. Facultad de Medicina. Instituto de Oncología "Dr. Ángel Roffo". Unidad de Transferencia Genética; ArgentinaFil: Combe, Kristell. École Nationale Vétérinaire d'Alfort; FranciaFil: Duchene, Adriana Graciela. Universidad de Buenos Aires. Facultad de Ciencias Veterinarias; ArgentinaFil: Wei, Ming X. École Nationale Vétérinaire d'Alfort; FranciaFil: Glikin, Gerardo Claudio. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad de Buenos Aires. Facultad de Medicina. Instituto de Oncología "Dr. Ángel Roffo". Unidad de Transferencia Genética; ArgentinaFil: Finocchiaro, Liliana Maria Elena. Universidad de Buenos Aires. Facultad de Medicina. Instituto de Oncología "Dr. Ángel Roffo". Unidad de Transferencia Genética; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentin

La délétion de 4E-BP1 et 4E-BP2 permet le maintien de la masse, de la force et de la synthèse protéique musculaires chez des souris âgées mâles

La délétion de 4E-BP1 et 4E-BP2 permet le maintien de la masse, de la force et de la synthèse protéique musculaires chez des souris âgées mâles. Journée Scientifique du CRNH Auvergn

F₂-isoprostane and PGF_2α immunostaning in adjacent breast tissue to tumor or breast tumor tissue.

<p>Adjacent breast tissue to tumor or breast tumor tissue labeled by indirect immunofluorescence for A/ F₂-isoprostane and B/ PGF_2α (green) with DAPI as nuclear counterstain (blue).</p