References of "Mathy, Grégory"
     in
Bookmark and Share    
Full Text
See detailEffects of dietary methylmercury on the Zebrafish (Danio rerio) liver proteome
Brésart, David ULg; Fourdrilis, Séverine; Mathy, Grégory ULg et al

Poster (2010, July 19)

Methylmercury (MeHg) is an aquatic pollutant. It is produced from HgS by the action of sulphate-reducing bacteria and is released in fresh waters. MeHg is bioaccumulated through the trophic chain and is ... [more ▼]

Methylmercury (MeHg) is an aquatic pollutant. It is produced from HgS by the action of sulphate-reducing bacteria and is released in fresh waters. MeHg is bioaccumulated through the trophic chain and is known to cause different health troubles (trembling, memory loss, anemia and kidney deficiency). Toxic exogenous substances, such as MeHg, are transformed by liver’s metabolic pathway, making this the starting point of vertebrate detoxication. Almost 50% of MeHg assimilated in hepatocytes is accumulated in mitochondria (Ware et al.,1975) and It has been suggested that it may uncouples OXPHOS (Mori et al., 2007). The aim of this study was to identify the proteomics modifications of the liver mitochondrial proteome in response to a chronic MeHg intoxication by using the 2D DIGE methodology (Figure 1). Fishes were fed with two different contaminated diets (6.5 and 13.5 µg of MeHgCl / g of dry food.). We have also performed functional assays in order to confirm the MeHg uncoupling effect on Salmo truita liver mitochondria. [less ▲]

Detailed reference viewed: 53 (9 ULg)
Full Text
See detailProteomic evolution of s.cerevisiae during chronological aging
Blomme, Arnaud ULg; Mac Cord, Allan ULg; Sluse, Francis ULg et al

Poster (2010, July 19)

Opposite to the replicative aging, which refers to the exponential decline in the capacity of a single cell to divide, chronological aging of the yeast Saccharomyces cerevisiae refers to the time period a ... [more ▼]

Opposite to the replicative aging, which refers to the exponential decline in the capacity of a single cell to divide, chronological aging of the yeast Saccharomyces cerevisiae refers to the time period a yeast cell can survive in a non-dividing state. In 2006, Allen and co-workers reported that yeast cells evolve into two cell types during stationary phase: a high density population defined as quiescent cells (Q) and a low density population defined as non-quiescent (NQ) cells. These two populations mainly differ by their viability, measured as the ability to form colonies when platted on Petri dishes, and can be separated by differential centrifugation on density gradient. In this work, we used the quantitative proteomics technique of 2DDIGE (two Dimensional Differential In-Gel Electrophoresis) to compare the evolution of the yeast cellular soluble proteome during chronological aging. We also checked the impact of the carbon source on stationary-phase cell differentiation. As the ratio of Q/NQ cells is decreasing with time, we have selected three distinct periods: 0 day (32h after outset of yeast culture on glucose, 100% of Q cells), 7 days (50% of Q cells) and 14 days (100% of NQ cells) to realize 3 proteomics comparisons (fig 1). [less ▲]

Detailed reference viewed: 61 (14 ULg)
Full Text
Peer Reviewed
See detailDynamics of the Dictyostelium discoideum mitochondrial proteome during vegetative growth, starvation and early stages of development
Czarna, Malgorzata; Mathy, Grégory ULg; Mac Cord, Allan ULg et al

in Proteomics (2010), 9

In this study a quantitative comparative proteomics approach has been used to analyze the D. discoideum mitochondrial proteome variations during vegetative growth, starvation and the early stages of ... [more ▼]

In this study a quantitative comparative proteomics approach has been used to analyze the D. discoideum mitochondrial proteome variations during vegetative growth, starvation and the early stages of development. Application of 2D-DIGE technology allowed the detection of around 2000 protein spots on each two-dimensional gel with 180 proteins exhibiting significant changes in their expression level. In total, 96 proteins (51 unique and 45 redundant) were unambiguously identified. We show that the D. discoideum mitochondrial proteome adaptations mainly affect energy metabolism enzymes (the Krebs cycle, anaplerotic pathways, the oxidative phosphorylation system and energy dissipation), proteins involved in developmental and signalling processes as well as in protein biosynthesis and fate. The most striking observations were the opposite regulation of expression of citrate synthase and aconitase and the very large variation in the expression of the alternative oxidase (AOX) that highlighted the importance of citrate and AOX in the physiology of the development of D. discoideum. Mitochondrial energy states measured in vivo with MitoTracker Orange CMTMRos showed an increase in mitochondrial membrane polarisation during D. discoideum starvation and starvation-induced development. [less ▲]

Detailed reference viewed: 159 (39 ULg)
Full Text
Peer Reviewed
See detailProteomic and functional characterization of a Chlamydomonas reinhardtii mutant lacking the mitochondrial alternative oxidase 1
Mathy, Grégory ULg; Cardol, Pierre ULg; Dinant, Monique et al

in Journal of Proteome Research (2010), 9

In the present work we have isolated by RNA interference and characterized at the functional and the proteomic levels a Chlamydomonas reinhardtii strain devoid of the mitochondrial alternative oxidase ... [more ▼]

In the present work we have isolated by RNA interference and characterized at the functional and the proteomic levels a Chlamydomonas reinhardtii strain devoid of the mitochondrial alternative oxidase (AOX). The AOX-deficient strain displays a doubling of the cell volume and biomass without any alteration of the generation time, a significantly higher ROS production, no change in total respiration rate, and a slight decrease of the photosynthesis efficiency. In order to identify the molecular adaptation underlying these phenotypical effects, we carried out a comparative proteomic study at the level of the mitochondrial and cellular soluble proteomes. Our results indicate a strong up-regulation of the ROS scavenging systems and important modifications of proteins involved in the primary metabolism, namely an increase of enzymes involved in anabolic pathways and a concomitant general down-regulation of enzymes of the main catabolic pathways. [less ▲]

Detailed reference viewed: 202 (97 ULg)
Full Text
Peer Reviewed
See detailPlasticity of the mitoproteome to nitrogen sources (nitrate and ammonium) in Chlamydomonas reinhardtii: the logic of Aox1 gene localization
Gérin, Stéphanie ULg; Mathy, Grégory ULg; Blomme, Arnaud ULg et al

in Biochimica et Biophysica Acta-Bioenergetics (2010), 1797

Nitrate and ammonium constitute primary inorganic nitrogen sources that can be incorporated into carbon skeletons in photosynthetic eukaryotes. In Chlamydomonas, previous studies and the present one ... [more ▼]

Nitrate and ammonium constitute primary inorganic nitrogen sources that can be incorporated into carbon skeletons in photosynthetic eukaryotes. In Chlamydomonas, previous studies and the present one showed that the mitochondrial AOX is up-regulated in nitrate-grown cells in comparison with ammonium-grown cells. In this work, we have performed a comparative proteomic analysis of the soluble mitochondrial proteome of Chlamydomonas cells growth either on nitrate or ammonium. Our results highlight important proteomics modifications mostly related to primary metabolism in cells grown on nitrate. We could note an up-regulation of some TCA cycle enzymes and a down-regulation of cytochrome c1 together with an up-regulation of l-arginine and purine catabolism enzymes and of ROS scavenging systems. Hence, in nitrate-grown cells, AOX may play a dual role: (1) lowering the ubiquinone pool reduction level and (2) permitting the export of mitochondrial reducing power under the form of malate for nitrate and nitrite reduction. This role of AOX in the mitochondrial plasticity makes logical the localization of Aox1 in a nitrate assimilation gene cluster. [less ▲]

Detailed reference viewed: 102 (45 ULg)
Full Text
See detailPerturbations de la phosphorylation oxydative : réponses protéomiques et conséquences métaboliques
Mathy, Grégory ULg

Doctoral thesis (2009)

La phosphorylation oxydative et ses partenaires privilégiés, que sont les voies métaboliques énergétiques principales, sont finement régulés au niveau thermodynamique en vertu de la loi d’action des ... [more ▼]

La phosphorylation oxydative et ses partenaires privilégiés, que sont les voies métaboliques énergétiques principales, sont finement régulés au niveau thermodynamique en vertu de la loi d’action des masses. Ces processus de régulations enzymatiques s’accompagnent cependant de « soupapes » de sécurité qui permettent, le cas échéant, de maintenir de manière optimale la bonne opération de l’ensemble de ce système et donc d’assurer une balance metabolique adequate entre l’offre et la demande. Par une approche de protéomique comparée, nous avons étudiés les effets de ces différents types de stress tant au niveau mitochondrial que cellulaire afin de mettre en évidence d’éventuelles adaptations initiées par la cellule en réponse à ces perturbations Dans la première partie nous avons etudie les effets de l’oxydase alternative sur le protéome mitochondrial et cellulaire. La première etude consiste en une création de la fonction AOX au niveau mitochondrial dans un organisme modèle ne l’exprimant pas naturellement : Saccharomyces cerevisiae. Deux approches protéomiques ont été utilisees, à savoir le 2D DIGE et le SILAC. La seconde étude concernant AOX consiste en l’analyse des effets d’une perte de fonction de la protéine obtenue par ARN interférence chez l’algue unicellulaire Chlamydomonas reinhardtii. La seconde partie de notre travail sera consacrée à l’étude des modifications protéomiques accompagnant l’initiation de la thermogenèse non frissonnante ainsi que l’acclimatation au froid au niveau du tissu adipeux brun. Cette étude à été réalisée chez le rat et chez la souris. Les effets de l’acclimatation au froid chez des souris UCP-1 KO ont ete aussi étudiés et comparés aux effets chez des souris normales. [less ▲]

Detailed reference viewed: 148 (43 ULg)
Full Text
See detailProteomic characterization of a Chlamydomonas reinhardtii mutant lacking the mitochondrial alternative oxidase
Mathy, Grégory ULg

Conference (2009, September 27)

Conférence réalisée sur la carractérisation d'un mutant AOX- chez l'algue unicellulaire Chlamydomonas reinhardtii

Detailed reference viewed: 13 (3 ULg)
Full Text
See detailIntroduction to the comparative proteomics and its application to mitochondria
Mathy, Grégory ULg

Scientific conference (2008, November 19)

conférence d'introduction à la protéomique comparée donnée dans le cadre d'un séminaire de l'institut matéria médica de l'université de Pékin

Detailed reference viewed: 41 (3 ULg)
Full Text
See detailS13.45 Chlamydomonas reinhardtii mitoproteome adaptation in response to inactivation of the energy-dissipating alternative oxidase 1 by RNA interference
Cloes, Marie ULg; Mathy, Grégory ULg; Cardol, Pierre ULg et al

in Biochimica et Biophysica Acta (BBA) - Bioenergetics, Volume 1777, Supplement 1, 19 July 2008, Page S99 (2008, July 18), 1777(Supplement 1), 99

Detailed reference viewed: 54 (14 ULg)
Full Text
See detailChlamydomonas reinhardtii proteomics adaptations in response to the absence of the energy-dissipating alternative oxidase
Mathy, Grégory ULg

Poster (2008, May 28)

The Alternative oxidase (AOX) is an ubiquinol-oxygen oxidoreductase found in the mitochondrial inner membrane of plants, fungi and protists. In mitochondria, AOX activation creates an electron ... [more ▼]

The Alternative oxidase (AOX) is an ubiquinol-oxygen oxidoreductase found in the mitochondrial inner membrane of plants, fungi and protists. In mitochondria, AOX activation creates an electron partitioning between the cytochrome pathway (CIII + CIV) and AOX. This partitioning leads to a decrease of proton pumping efficiency by the respiratory chain complexes per O2 consumed. Two closely related physiological roles are attributed to AOX: First, AOX in conjunction with rotenone insensitive NADH dehydrogenases, generates a fully non-coupled (energy dissipative) electron transport chain in the mitochondria, which is believed to play an important role in regenerating oxidized cofactors required for others metabolic demands. The second proposed role of AOX is to prevent an important increase the QR/Qt ratio and consequently, to prevent reactive oxygen species (ROS) production. In Chlamydomonas reinhartii AOX is encoded by two different genes, the AOX1 gene being much more transcribed than AOX2. In addition, the expression of the AOX1 gene is generally unresponsive to a number of known AOX allosteric effectors, but is down-regulated by ammonium and up-regulated by nitrate. In the present work, we performed a comparative proteomic study of isolated mitochondria by using the 2D-DIGE methodology to evidence the effects of AOX1 silencing on Chlamydomonas mitochondrial soluble proteome cultivated on nitrate in myxotrophic conditions [less ▲]

Detailed reference viewed: 34 (4 ULg)
Full Text
Peer Reviewed
See detailMitochondrial comparative proteomics: Strenghts and Pitfalls
Mathy, Grégory ULg; Sluse, Francis ULg

in Biochimica et Biophysica Acta-Bioenergetics (2008), 1977

In this review, we describe the various techniques available to carry out valid comparative proteomics, their advantages and their disadvantages according to the goal of the research. Two-dimensional ... [more ▼]

In this review, we describe the various techniques available to carry out valid comparative proteomics, their advantages and their disadvantages according to the goal of the research. Two-dimensional electrophoresis and 2D-DIGE are compared to shotgun proteomics and SILE. We give our opinion on the best fields of application in the domain of comparative proteomics. We emphasize the usefulness of these new tools, providing mass data to study physiology and mitochondrial plasticity when faced with a specific mitochondrial insufficiency or exogenic stress. We illustrate the subject with results obtained in our laboratory specifying the importance of an approach of comparative proteomics combined from mitochondria and from the cell, which makes it possible to obtain important information on the status of the mitochondrial function at the cellular level. Finally, we draw attention to the dangers of the extrapolation of proteomic data to metabolic flows which requires the greatest care [less ▲]

Detailed reference viewed: 37 (13 ULg)
Full Text
See detailEffet de l’expression hétérologue d’une oxydase alternative sur le protéome mitochondrial et cellulaire de Saccharomyces cerevisiae
Mathy, Grégory ULg

Conference (2007, June 15)

L’oxydase alternative (AOX) est une ubiquinol-oxygène oxido-réductase qui au niveau mitochondrial, catalyse l’oxydation de l’ubiquinol en transférant directement ses électrons à l’oxygène. De part son ... [more ▼]

L’oxydase alternative (AOX) est une ubiquinol-oxygène oxido-réductase qui au niveau mitochondrial, catalyse l’oxydation de l’ubiquinol en transférant directement ses électrons à l’oxygène. De part son activité catalytique, cette protéine entre en compétition avec le complexe III et est donc un système dissipateur d’énergie puisque les électrons transférés par AOX à l’oxygène ne contribueront pas à l’établissement du gradient électrochimique de protons par la voie des cytochromes. Dans cette étude, nous avons voulu déterminer l’impact de l’expression hétérologue d’AOX chez un organisme qui en est naturellement dépourvu : Saccharomyces cerevisiae. L’expression d’AOX chez S. cerevisiae est fonctionnelle et conduit à une augmentation du temps de génération de 30% par rapport à la souche contrôle. De manière à identifier les voies métaboliques affectées par l’expression d’AOX chez la levure, nous avons réalisés une étude protéomique sur le protéome mitochondrial et cellulaire par l’approche SILAC. Le SILAC (stable isotopic labelling by amino-acid in cell culture) est une technique de protéomique comparative qui permet de calculer directement les changements de niveau d’expression des protéines par spectrométrie de masse, contrairement aux gels 2D, ou les changements sont estimés par densitométrie. Cette technique se base sur l’incorporation d’un acide aminé « lourd » ou « léger » lors de la traduction des protéines lors des cultures cellulaire. L’incorporation de ces acides aminé va induire en spectrométrie de masse, un décalage de masse entre deux peptides de même séquence et rendre possible directement la comparaison des niveau d’expression a calculant le rapport d’intensité des deux pics. En comparant le protéomes mitochondrial, nous avons remarqué une augmentation générale du niveau d’expression de tous les enzymes du cycle de Krebs. Cette augmentation est accompagnée par une augmentation du niveau d’expression des NADH déshydrogénases interne et une diminution de la NADH déshydrogénase externe suggérant une augmentation de l’entrée des électrons dans la chaîne respiratoire via la production d’équivalents réducteurs par le cycle de Krebs plutôt que par les équivalent réducteurs issus du cytoplasme. En comparant les protéomes cellulaires, nous avons observés une diminution globale de toutes les protéines mitochondriales suggérant une diminution de la masse mitochondriales par cellules. Cette diminution est accompagnée par une augmentation générale de la glycolyse d’un facteur 2,5. [less ▲]

Detailed reference viewed: 37 (4 ULg)
Full Text
See detailMitochondrion plasticity evidenced by coupled comparisons of mitochondrial and cellular proteomes
Mathy, Grégory ULg

Poster (2007, May 16)

Mitochondria are key organelles in primary metabolism: they are the main source of energy production and the starting point of important biosynthetic pathways. Thus the control of the mitochondrial ... [more ▼]

Mitochondria are key organelles in primary metabolism: they are the main source of energy production and the starting point of important biosynthetic pathways. Thus the control of the mitochondrial function is a prerequisite for cellular survival in front of a wide spectrum of exogenous or endogenous stresses. By using the SILAC method, we have investigated the yeast mitochondrial and cellular proteome adaptation to the heterologous expression of a mitochondrial alternative oxidase (AOX). AOX is an energy dissipating enzyme that catalyses the re-oxidation of ubiquinol within the respiratory chain and compete with the Cytochrome pathway for electrons and thus, prevents proton pumping, and consequently leads to a decrease in ATP synthesis. [less ▲]

Detailed reference viewed: 17 (4 ULg)
Full Text
Peer Reviewed
See detailMitoproteome plasticity of rat brown adipocytes in response to cold acclimation
Navet, Rachel ULg; Mathy, Grégory ULg; Douette, Pierre ULg et al

in Journal of Proteome Research (2007), 6(1), 25-33

Cold acclimation induces an adaptative increase in respiration in brown adipose tissue (BAT). A comparative analysis by two-dimensional differential in-gel electrophoresis of mitochondrial protein ... [more ▼]

Cold acclimation induces an adaptative increase in respiration in brown adipose tissue (BAT). A comparative analysis by two-dimensional differential in-gel electrophoresis of mitochondrial protein patterns found in rat control and cold-acclimated BAT was performed. A total of 58 proteins exhibiting significant differences in their abundance was unambiguously identified. Proteins implicated in the major catabolic pathways were up-regulated as were ATP synthase and mitofilin. Moreover, these results support the fact that adipocytes can balance their ATP synthesis and their heat production linked to UCP1-sustained uncoupling. [less ▲]

Detailed reference viewed: 52 (10 ULg)
Full Text
See detailThe Saccharomyces cerevisiae mitoproteome plasticity in response to recombinant alternative ubiquinol oxidase
Mathy, Grégory ULg

Poster (2006, July 20)

The energy-dissipating alternative oxydase (AOX) from Hansenula anomala was expressed in Saccharomyces cerevisiae. We have found that the recombinant product is properly addressed to the mitochondria ... [more ▼]

The energy-dissipating alternative oxydase (AOX) from Hansenula anomala was expressed in Saccharomyces cerevisiae. We have found that the recombinant product is properly addressed to the mitochondria where it was functional. A comparative analysis by two-dimensional differential in-gel electrophoresis (2D-DIGE) of mitochondrial protein patterns found in wild-type and recombinant AOX strains was performed. This analysis has shown that AOX expression affects energy-related enzymes in a very specific manner: 60 proteins exhibiting a significant difference in their abundance were identified and were implicated in major metabolic pathways such as Krebs cycle and amino-acid biosynthesis. At the level of the respiratory chain, we found a ~1.4-fold increase in the proton pumping complex III (ubiquinol-cytochrome c oxidoreductase), which competes with AOX for the reduced Q, as well as a ~1.7-fold increase in the succinate dehydrogenase that delivers electrons produced by the reduction of succinate to the Q pool. In addition, the NADH-cytochrome c reductase (MCR1) that transfers electrons from the externally-produced NADH directly to cytochrome c was ~1.4-fold greater in AOX+ mitochondria. This increase in MCR1 could force electrons to pass through the cytochrome c oxidase, the other proton pumps of the yeast respiratory chain. Up-regulation of the complex III as well as of MCR1 would influence the electron partitioning at the level of the Q pool in favour of the cytochrome pathway in order to diminish the impact of recombinant AOX on oxidative phosphorylation and energy conservation. Surprisingly, this up-regulation of the respiratory-chain was associated with a down-regulation of the ATP synthase complex. This decrease in ATP synthase content would allow the establishment of a novel steady state between the rate of ΔμH+ building and the rate of ΔμH+ consumption, favourable to the ATP synthase to perform ATP synthesis [less ▲]

Detailed reference viewed: 13 (1 ULg)
Full Text
Peer Reviewed
See detailSaccharomyces cerevisiae mitoproteome plasticity in response to recombinant alternative ubiquinol oxidase
Mathy, Grégory ULg; Navet, Rachel ULg; Gerkens, Pascal et al

in Journal of Proteome Research (2006), 5(2), 339-348

The energy-dissipating alternative oxidase (AOX) from Hansenula anomala, was expressed in Saccharomyces cerevisiae. The recombinant AOX was functional. A comparative analysis by two-dimensional ... [more ▼]

The energy-dissipating alternative oxidase (AOX) from Hansenula anomala, was expressed in Saccharomyces cerevisiae. The recombinant AOX was functional. A comparative analysis by two-dimensional differential in-gel electrophoresis (2D-DIGE) of mitochondrial protein patterns found in wild-type and recombinant AOX strains was performed. 60 proteins exhibiting a significant difference in their abundance were identified. Interestingly, proteins implicated in major metabolic pathways such as Krebs cycle and amino acid biosynthesis were up-regulated. Surprisingly, an up-regulation of the respiratory-chain complex III was associated with a down-regulation of the ATP synthase complex. [less ▲]

Detailed reference viewed: 90 (13 ULg)
Full Text
Peer Reviewed
See detailMitochondrial UCPs: New insights into regulation and impact
Sluse, Francis ULg; Jarmuszkiewicz, Wieslawa; Navet, Rachel ULg et al

in Biochimica et Biophysica Acta-Bioenergetics (2006), 1757(5-6, Suppl 1), 101

Uncoupling proteins (UCPs) are mitochondrial inner membrane proteins sustaining an inducible proton conductance. They weaken the proton electrochemical gradient built up by the mitochondrial respiratory ... [more ▼]

Uncoupling proteins (UCPs) are mitochondrial inner membrane proteins sustaining an inducible proton conductance. They weaken the proton electrochemical gradient built up by the mitochondrial respiratory chain. Brown fat UCP1 sustains a free fatty acid (FA)-induced purine nucleotide (PN)-inhibited proton conductance. Inhibition of the proton conductance by PN has been considered as a diagnostic of UCP activity. However, conflicting results have been obtained in isolated mitochondria for UCP homologues (i.e., UCP2, UCP3, plant UCP, and protist UCP) where the FFA-activated proton conductance is poorly sensitive to PN under resting respiration conditions. Our recent work clearly indicates that the membranous coenzyme Q, through its redox state, represents a regulator of the inhibition by PN of FFA-activated UCP1 homologues under phosphorylating respiration conditions. Several physiological roles of UCPs have been suggested, including a control of the cellular energy balance as well as the preventive action against oxidative stress. In this paper, we discuss new information emerging from comparative proteomics about the impact of UCPs on mitochondrial physiology, when recombinant UCP1 is expressed in yeast and when UCP2 is over-expressed in hepatic mitochondria during steatosis [less ▲]

Detailed reference viewed: 70 (13 ULg)