Editorial. Neurodegeneration, Neurogenesis, and Oxidative Stress

International audienc

Proteasomes associated with the Blm10 activator protein antagonize mitochondrial fission through degradation of the fission protein Dnm1

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The Oxygen Paradox, the French Paradox, and age-related diseases

open46openDavies, Joanna M. S.; Cillard, Josiane; Friguet, Bertrand; Cadenas, Enrique; Cadet, Jean; Cayce, Rachael; Fishmann, Andrew; Liao, David; Bulteau, Anne-Laure; Derbré, Frédéric; Rébillard, Amélie; Burstein, Steven; Hirsch, Etienne; Kloner, Robert A.; Jakowec, Michael; Petzinger, Giselle; Sauce, Delphine; Sennlaub, Florian; Limon, Isabelle; Ursini, Fulvio; Maiorino, Matilde; Economides, Christina; Pike, Christian J.; Cohen, Pinchas; Salvayre, Anne Negre; Halliday, Matthew R.; Lundquist, Adam J.; Jakowec, Nicolaus A.; Mechta-Grigoriou, Fatima; Mericskay, Mathias; Mariani, Jean; Li, Zhenlin; Huang, David; Grant, Ellsworth; Forman, Henry J.; Finch, Caleb E.; Sun, Patrick Y.; Pomatto, Laura C. D.; Agbulut, Onnik; Warburton, David; Neri, Christian; Rouis, Mustapha; Cillard, Pierre; Capeau, Jacqueline; Rosenbaum, Jean; Davies, Kelvin J. A.Davies, Joanna M. S.; Cillard, Josiane; Friguet, Bertrand; Cadenas, Enrique; Cadet, Jean; Cayce, Rachael; Fishmann, Andrew; Liao, David; Bulteau, Anne-Laure; Derbré, Frédéric; Rébillard, Amélie; Burstein, Steven; Hirsch, Etienne; Kloner, Robert A.; Jakowec, Michael; Petzinger, Giselle; Sauce, Delphine; Sennlaub, Florian; Limon, Isabelle; Ursini, Fulvio; Maiorino, Matilde; Economides, Christina; Pike, Christian J.; Cohen, Pinchas; Salvayre, Anne Negre; Halliday, Matthew R.; Lundquist, Adam J.; Jakowec, Nicolaus A.; Mechta-Grigoriou, Fatima; Mericskay, Mathias; Mariani, Jean; Li, Zhenlin; Huang, David; Grant, Ellsworth; Forman, HENRY J.; Finch, Caleb E.; Sun, Patrick Y.; Pomatto, Laura C. D.; Agbulut, Onnik; Warburton, David; Neri, Christian; Rouis, Mustapha; Cillard, Pierre; Capeau, Jacqueline; Rosenbaum, Jean; Davies, Kelvin J. A

Le protéasome (implication dans le vieillissement et le stress oxydant)

PARIS7-Bibliothèque centrale (751132105) / SudocSudocFranceF

Rôle des protéases Pim1/Lon et ClpP dans la mitochondrie ( implication en conditions de stress et dans le vieillissement)

Un dysfonctionnement mitochondrial a été mis en cause dans le processus de vieillissement, en lien avec une augmentation du niveau de stress oxydant et une accumulation de protéines oxydées dans les cellules. Les systèmes protéolytiques occupent une place importante en éliminant les protéines altérées produites en condition de stress. Dans le cytosol, le protéasome constitue le principal système de dégradation des protéines oxydées. Dans les mitochondries, les protéases Pim1/Lon et ClpP sont localisées dans la matrice et participent au renouvellement des protéines endommagées. Plusieurs études soulignent leur importance dans la réponse au stress dans la mitochondrie. La protéase Pim1/Lon est également impliquée dans le maintien des fonctions mitochondriales. Mon objectif pendant cette thèse a été de préciser le rôle de ces deux protéases dans la mitochondrie, notamment en conditions de stress. L implication de la protéase Pim1 dans le vieillissement a aussi été analysée. Nous avons identifié les substrats endogènes de la protéase Pim1 (S. cerevisiae) en utilisant un modèle de levure 0 (dépourvu d ADNmt). Des protéines partenaires de Pim1 ont également été obtenues. Ce travail a permis de mettre en évidence le rôle prépondérant de la protéase Pim1 en condition de stress spécifique de la mitochondrie. Des précisions quant à ses fonctions dans l organite ont aussi été apportées. Dans un deuxième temps, une diminution de la longévité a été observée chez une souche pim1. Etonnamment, ce vieillissement prématuré met en jeu un dysfonctionnement cytosolique. Nous avons ensuite réussi à reverser ce phénotype de vieillissement par surexpression d Hsp104, validant de cette manière les mécanismes mis à jour. D autre part, nous avons établi des lignées de cellules humaines permettant d éteindre l une ou l autre des protéases Lon ou ClpP par une approche shRNA inductible. Ces cellules ont été caractérisées en conditions basales, en portant une attention particulière aux fonctions mitochondriales, en lien avec la prolifération et la mort cellulaire. A l exception d une baisse de prolifération, aucun phénotype n a été observé dans les cellules déficientes en ClpP. En revanche, l extinction de la protéase Lon révèle une altération du réseau mitochondrial et semble indiquer une accumulation de protéines non dégradées dans les mitochondries. A terme, ces modèles cellulaires présentent un intérêt pour identifier les substrats de ces deux protéases et pour évaluer leur rôle en conditions de stressPARIS-BIUSJ-Physique recherche (751052113) / SudocSudocFranceF

Biomedical and Pharmaceutical Applications

International audienceThis chapter reviews the current knowledge of important functions of selenium (Se) and selenoproteins in physiology and pathology in human. The outcome of the different clinical trials reveals the need for a better understanding of Se biology. The physiology of Se depends on its continuous supply to the body and its optimal distribution to tissues. The development and application of mass spectrometry imaging (MSI) techniques are of great interest in cancer research and diagnosis to study elemental distributions in biological tissue samples at microscopic level. The ability to record spatial accumulation of multiple analytes in tissue samples under native conditions and to directly correlate obtained images with histological features has made MSI an invaluable analytical tool. The chapter concentrates on literature about manganese (Mn) speciation targeting neurodegeneration effects, first, in human samples, such as serum or cerebrospinal fluid (CSF) samples, where some studies were summarized in 2007. It also presents a case study of Alzheimer's disease

Neurodegeneration, Neurogenesis, and Oxidative Stress 2015

International audienc

Mitochondrial proteases and protein quality control in ageing and longevity

International audienceMitochondria have been implicated in the ageing process and the lifespan modulation of model organisms. Mitochondria are the main providers of energy in eukaryotic cells but also represent both a major source of reactive oxygen species and targets for protein oxidative damage. Since protein damage can impair mitochondrial function, mitochondrial proteases are critically important for protein maintenance and elimination of oxidized protein. In the mitochondrial matrix, protein quality control is mainly achieved by the Lon and Clp proteases which are also key players in damaged mitochondrial proteins degradation. Accumulation of damaged macromolecules resulting from oxidative stress and failure of protein maintenance constitutes a hallmark of cellular and organismal ageing and is believed to participate to the age-​related decline of cellular function. Hence, age-​related impairment of mitochondrial protein quality control may therefore contribute to the age-​associated build-​up of oxidized protein and alterations of mitochondrial redox and protein homeostasis

Comparison of analytical methods using enzymatic activity, immunoaffinity and selenium-specific mass spectrometric detection for the quantitation of glutathione peroxidase 1

International audienceGlutathione peroxidase 1 (Gpx1), one of the most responsive selenoproteins to the variation of selenium concentration, is often used to evaluate ”selenium status” at a cellular or organismal level. The four major types of analytical methodologies to quantify Gpx1 were revisited. They include (i) an enzymatic assay, (ii, iii) polyacrylamide gel electrophoresis (PAGE) with (ii) western blot detection of protein or (iii) inductively coupled plasma mass spectrometry (ICP MS) detection of selenium, and (iv) size-exclusion chromatography with ICP MS detection. Each of the four methods was optimized for the quantification of Gpx1 with maximum sensitivity. The methods based on the enzymatic and immunodetection offer a much higher sensitivity but their accuracy is compromised by the limited selectivity and limited dynamic range. The advantages, drawbacks and sources of error of each technique are critically discussed and the need for the cross-validation of the results using the different techniques to assure the quality assurance of quantitative analysis is emphasized

Glycine contributes to the control of hepatic response to insulin by promoting mitochondrial-endoplasmic reticulum interactions

International audienceAbstract Introduction Determinants of health and diseases in humans involve complex interactions between diet, gut microbiota and host metabolism. The liver is a major organ that coordinates host adaptations to environmental factors. Mitochondria and endoplasmic reticulum tightly regulate liver nutrient sensing and metabolic adaptations, shaping its metabolic flexibility. Both organelles interact through contact points (named MAMs) in order to exchange calcium and lipids, and MAMs’ integrity settles metabolic flexibility of the liver. Disrupted MAMs’ integrity in obesity is linked to liver steatosis and insulin resistance. This occurs in association with alterations circulating amino acid profiles, among which glycine. Meta-analyses showed that the low plasma glycine concentration observed in obesity is a predictive factor for developing type 2 diabetes. We thus aimed at exploring whether glycine could participate to the regulation of the hepatic response to insulin and whether mechanisms may involve regulation of mitochondrial-ER (MAMs) interactions. Materials and Methods The study was carried out in 12 week-old male C57B16J mice fed a standard chow (n = 12/group, 36 total) in accordance with the French guidelines for the care and use of animals. Glycine (1.2g/kg) was provided for 3 days in drinking water vs. water vs. isonitrogenous placebo amino acids. Liver was collected after an overnight fast, 15 min after ip injection of saline (n = 6/group) or insulin (0.75U/kg, n = 6/group). Liver samples were fixed in glutaraldehyde/cacodylate for quantifying MAMs by transmission electronic microscopy. Fractions enriched in MAMs were isolated by differential ultracentrifugation on fresh tissue for Western Blot explorations. Insulin response was assessed through Akt phosphorylation at Ser473. Results Glycine supplementation increased the percentage of interaction between ER and mitochondria (compare to mitochondrial surface) for all spacing from 10 to 50 nm. Thus, glycine supplementation induced a 45% increase in mitochondrial-ER (MAMs) interactions compared to other groups (p < 0.001). In agreement to the improved MAMs’ integrity, insulin response was enhanced by 50% after glycine supplementation compared to other groups (p < 0.05). Finally, protein analysis of the MAMs' fraction corroborates the importance of PP2A as a key enzyme regulating MAMs’ integrity. Conclusion Glycine is therefore an interesting nutritional actor that can play a crucial role in regulating the integrity of MAMs in the liver, thus contributing to the control of the insulin response