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Publications Départements Biologie Cellulaire


  • T. Avin-Wittenberg, F. Baluška, P. V. Bozhkov, P. H. Elander, A. R. Fernie, G. Galili, A. Hassan, D. Hofius, E. Isono, R. Le Bars, C. Masclaux-Daubresse, E. A. Minina, H. Peled-Zehavi, N. S. Coll, L. M. Sandalio, B. Satiat-Jeunemaitre, A. Sirko, P. S. Testillano, et H. Batoko, « Autophagy-related approaches for improving nutrient use efficiency and crop yield protection », Journal of Experimental Botany, vol. 69, nᵒ 6, p. 1335-1353, mars 2018.
    Mots-clés : BIOCELL, CYTO, DYNBSJ, PF, PHOT.

  • D. Carmona-Gutierrez, M. A. Bauer, A. Zimmermann, A. Aguilera, N. Austriaco, K. Ayscough, R. Balzan, S. Bar-Nun, A. Barrientos, P. Belenky, M. Blondel, R. J. Braun, M. Breitenbach, W. C. Burhans, S. Buettner, D. Cavalieri, M. Chang, K. F. Cooper, M. Côrte-Real, V. Costa, C. Cullin, I. Dawes, J. Dengjel, M. B. Dickman, T. Eisenberg, B. Fahrenkrog, N. Fasel, K. - U. Froehlich, A. Gargouri, S. Giannattasio, P. Goffrini, C. W. Gourlay, C. M. Grant, M. T. Greenwood, N. Guaragnella, T. Heger, J. Heinisch, E. Herker, J. M. Herrmann, S. Hofer, A. Jiménez-Ruiz, H. Jungwirth, K. Kainz, D. P. Kontoyiannis, P. Ludovico, S. Manon, E. Martegani, C. Mazzoni, L. A. Megeney, C. Meisinger, J. Nielsen, T. Nystroem, H. D. Osiewacz, T. F. Outeiro, H. - O. Park, T. Pendl, D. Petranovic, S. Picot, P. Polčic, T. Powers, M. Ramsdale, M. Rinnerthaler, P. Rockenfeller, C. Ruckenstuhl, R. Schaffrath, M. Segovia, F. F. Severin, A. Sharon, S. J. Sigrist, C. Sommer-Ruck, M. J. Sousa, J. M. Thevelein, K. Thevissen, V. Titorenko, M. B. Toledano, M. Tuite, F. - N. Voegtle, B. Westermann, J. Winderickx, S. Wissing, S. Woelfl, Z. J. Zhang, R. Y. Zhao, B. Zhou, L. Galluzzi, G. Kroemer, et F. Madeo, « Guidelines and recommendations on yeast cell death nomenclature », Microbial Cell, vol. 5, nᵒ 1, p. 4-31, janv. 2018.

  • G. Dubeaux, J. Neveu, E. Zelazny, et G. Vert, « Metal Sensing by the IRT1 Transporter-Receptor Orchestrates Its Own Degradation and Plant Metal Nutrition », Molecular Cell, vol. 69, nᵒ 6, p. 953-964.e5, mars 2018.
    Résumé : Plant roots forage the soil for iron, the concentration of which can be dramatically lower than those needed for growth. Soil iron uptake uses the broad metal spectrum IRT1 transporter that also transports zinc, manganese, cobalt, and cadmium. Sophisticated iron-dependent transcriptional regulatory mechanisms allow plants to tightly control the abundance of IRT1, ensuring optimal absorption of iron. Here, we uncover that IRT1 acts as a transporter and receptor (transceptor), directly sensing excess of its non-iron metal substrates in the cytoplasm, to regulate its own degradation. Direct metal binding to a histidine-rich stretch in IRT1 triggers its phosphorylation by the CIPK23 kinase and facilitates the subsequent recruitment of the IDF1 E3 ligase. CIPK23-driven phosphorylation and IDF1-mediated lysine-63 polyubiquitination are jointly required for efficient endosomal sorting and vacuolar degradation of IRT1. Thus, IRT1 directly senses elevated non-iron metal concentrations and integrates multiple substrate-dependent regulations to optimize iron uptake and protect plants from highly reactive metals.
    Mots-clés : Arabidopsis, BIOCELL, degradation, metal homeostasis, phosphorylation, plant, receptor, sensing, transceptor, transporter, UBINET, ubiquitin.

  • F. Giordano, « Non-vesicular lipid trafficking at the endoplasmic reticulum–mitochondria interface », Biochemical Society Transactions, p. BST20160185, mars 2018.

  • J. Marion, R. Le Bars, L. Besse, H. Batoko, et B. Satiat-Jeunemaitre, « Multiscale and Multimodal Approaches to Study Autophagy in Model Plants », Cells, vol. 7, nᵒ 1, janv. 2018.
    Résumé : Autophagy is a catabolic process used by eukaryotic cells to maintain or restore cellular and organismal homeostasis. A better understanding of autophagy in plant biology could lead to an improvement of the recycling processes of plant cells and thus contribute, for example, towards reducing the negative ecological consequences of nitrogen-based fertilizers in agriculture. It may also help to optimize plant adaptation to adverse biotic and abiotic conditions through appropriate plant breeding or genetic engineering to incorporate useful traits in relation to this catabolic pathway. In this review, we describe useful protocols for studying autophagy in the plant cell, taking into account some specificities of the plant model.
    Mots-clés : Arabidopsis, autophagosome, Autophagy, autophagy assays, BIOCELL, CYTO, DYNBSJ, methods, PHOT, plant cells, Tobacco.

  • N. Romero-Barrios et G. Vert, « Proteasome-independent functions of lysine-63 polyubiquitination in plants », The New Phytologist, vol. 217, nᵒ 3, p. 995-1011, févr. 2018.
    Résumé : Contents Summary 995 I. Introduction 995 II. The plant Ub machinery 996 III. From Ub to Ub linkage types in plants 997 IV. Increasing analytical resolution for K63 polyUb in plants 998 V. How to build K63 polyUb chains? 998 VI. Cellular roles of K63 polyUb in plants 999 VII. Physiological roles of K63 polyUb in plants 1004 VIII. Future perspectives: towards the next level of the Ub code 1006 Acknowledgements 1006 References 1007 SUMMARY: Ubiquitination is a post-translational modification essential for the regulation of eukaryotic proteins, having an impact on protein fate, function, localization or activity. What originally appeared to be a simple system to regulate protein turnover by the 26S proteasome is now known to be the most intricate regulatory process cells have evolved. Ubiquitin can be arranged in countless chain assemblies, triggering various cellular outcomes. Polyubiquitin chains using lysine-63 from ubiquitin represent the second most abundant type of ubiquitin modification. Recent studies have exposed their common function in proteasome-independent functions in non-plant model organisms. The existence of lysine-63 polyubiquitination in plants is, however, only just emerging. In this review, we discuss the recent advances on the characterization of ubiquitin chains and the molecular mechanisms driving the formation of lysine-63-linked ubiquitin modifications. We provide an overview of the roles associated with lysine-63 polyubiquitination in plant cells in the light of what is known in non-plant models. Finally, we review the crucial roles of lysine-63 polyubiquitin-dependent processes in plant growth, development and responses to environmental conditions.
    Mots-clés : Autophagy, BIOCELL, UBINET.

  • L. Shi, F. Koll, O. Arnaiz, et J. Cohen, « The Ciliary Protein IFT57 in the Macronucleus of Paramecium », The Journal of Eukaryotic Microbiology, vol. 65, nᵒ 1, p. 12-27, janv. 2018.
    Résumé : The intraflagellar transport IFT57 protein is essential for ciliary growth and maintenance. Also known as HIPPI, human IFT57 can be translocated to the nucleus via a molecular partner of the Huntingtin, Hip1, inducing gene expression changes. In Paramecium tetraurelia, we identified four IFT57 genes forming two subfamilies IFT57A/B and IFT57C/D arising from whole genome duplications. The depletion of proteins of the two subfamilies induced ciliary defects and IFT57A and IFT57C localized in basal bodies and cilia. We observed that IFT57A, but not IFT57C, is also present in the macronucleus and able to traffic toward the developing anlage during autogamy. Analysis of chimeric IFT57A-IFT57C-GFP-tagged proteins allowed us to identify a region of IFT57A necessary for nuclear localization. We studied the localization of the unique IFT57 protein of Paramecium caudatum, a species, which diverged from P. tetraurelia before the whole genome duplications. The P. caudatumIFT57C protein was excluded from the nucleus. We also analyzed whether the overexpression of IFT57A in Paramecium could affect gene transcription as the human protein does in HeLa cells. The expression of some genes was indeed affected by overexpression of IFT57A, but the set of affected genes poorly overlaps the set of genes affected in human cells.
    Mots-clés : ANGE, BIOCELL, BIOCIL, cilia, DBG, HIPPI, IFT57 /HIPPI, intraflagellar transport, intraflagellar transport (IFT), Macronucleus, MICMAC, Paramecium.

  • Z. Song, B. I. Iorga, P. Mounkoro, N. Fisher, et B. Meunier, « The antimalarial compound ELQ-400 is an unusual inhibitor of the <i>bc</i> <sub>1</sub> complex, targeting both <i>Q</i> <sub>o</sub> and <i>Q</i> <sub>i</sub> sites », FEBS Letters, mars 2018.

  • S. Merlot, V. Sanchez Garcia de la Torre, et M. Hanikenne, « Physiology and Molecular Biology of Trace Element Hyperaccumulation », in Agromining: Farming for Metals, A. Van der Ent, G. Echevarria, A. J. M. Baker, et J. L. Morel, Éd. Cham: Springer International Publishing, 2018, p. 93-116.


  • A. Agorio, J. Giraudat, M. W. Bianchi, J. Marion, C. Espagne, L. Castaings, F. Lelièvre, C. Curie, S. Thomine, et S. Merlot, « Phosphatidylinositol 3-phosphate–binding protein AtPH1 controls the localization of the metal transporter NRAMP1 in Arabidopsis », Proceedings of the National Academy of Sciences, p. 201702975, avr. 2017.
    Mots-clés : BIOCELL, DYNBSJ, late endosome, metal transport, MINION, NRAMP, phosphatidylinositol 3-phosphate, vacuole.

  • S. Ait-El-Mkadem, M. Dayem-Quere, M. Gusic, A. Chaussenot, S. Bannwarth, B. François, E. C. Genin, K. Fragaki, C. L. M. Volker-Touw, C. Vasnier, V. Serre, K. L. I. van Gassen, F. Lespinasse, S. Richter, G. Eisenhofer, C. Rouzier, F. Mochel, A. De Saint-Martin, M. - T. Abi Warde, M. G. M. de Sain-van der Velde, J. J. M. Jans, J. Amiel, Z. Avsec, C. Mertes, T. B. Haack, T. Strom, T. Meitinger, P. E. Bonnen, R. W. Taylor, J. Gagneur, P. M. van Hasselt, A. Rötig, A. Delahodde, H. Prokisch, S. A. Fuchs, et V. Paquis-Flucklinger, « Mutations in MDH2, Encoding a Krebs Cycle Enzyme, Cause Early-Onset Severe Encephalopathy », American Journal of Human Genetics, vol. 100, nᵒ 1, p. 151-159, 2017.

  • A. Arnal, C. Jacqueline, B. Ujvari, L. Leger, C. Moreno, D. Faugere, A. Tasiemski, C. Boidin-Wichlacz, D. Misse, F. Renaud, J. Montagne, A. Casali, B. Roche, F. Mery, et F. Thomas, « Cancer brings forward oviposition in the fly Drosophila melanogaster », Ecology and Evolution, vol. 7, nᵒ 1, p. 272-276, janv. 2017.
    Résumé : Hosts often accelerate their reproductive effort in response to a parasitic infection, especially when their chances of future reproduction decrease with time from the onset of the infection. Because malignancies usually reduce survival, and hence potentially the fitness, it is expected that hosts with early cancer could have evolved to adjust their life-history traits to maximize their immediate reproductive effort. Despite the potential importance of these plastic responses, little attention has been devoted to explore how cancers influence animal reproduction. Here, we use an experimental setup, a colony of genetically modified flies Drosophila melanogaster which develop colorectal cancer in the anterior gut, to show the role of cancer in altering life-history traits. Specifically, we tested whether females adapt their reproductive strategy in response to harboring cancer. We found that flies with cancer reached the peak period of oviposition significantly earlier (i.e., 2 days) than healthy ones, while no difference in the length and extent of the fecundity peak was observed between the two groups of flies. Such compensatory responses to overcome the fitness-limiting effect of cancer could explain the persistence of inherited cancer-causing mutant alleles in the wild.
    Mots-clés : BIOCELL, cancer, fecundity, life‐history strategy, METABO, reproduction.

  • A. Aubusson-Fleury, G. Balavoine, M. Lemullois, K. Bouhouche, J. Beisson, et F. Koll, « Centrin diversity and basal body patterning across evolution: new insights from Paramecium », Biology Open, avr. 2017.
    Résumé : First discovered in unicellular eukaryotes, centrins play crucial roles in basal body duplication and anchoring mechanisms. While the evolutionary status of the founding members of the family, Centrin2/Vfl2 and Centrin3/cdc31 has long been investigated, the evolutionary origin of other members of the family has received less attention. Using a phylogeny of ciliate centrins, we identify two other centrin families, the ciliary centrins and the centrins present in the contractile filaments (ICL centrins). In this paper, we carry on the functional analysis of still not well known centrins, the ICL1e subfamily identified in Paramecium, and show their requirement for correct basal body anchoring through interactions with Centrin2 and Centrin3. Using Paramecium as well as an Eukaryote-wide sampling of centrins from completely sequenced genomes, we revisited the evolutionary story of centrins. Their phylogeny shows that the centrins associated with the ciliate contractile filaments are widespread in eukaryotic lineages and could be as ancient as Centrin2 and Centrin3.
    Mots-clés : basal body anchoring, basal body assembly, BIOCELL, BIOCIL, centrin evolution, Ciliary centrins, ciliated epithelia polarity.

  • H. Bengueddach, M. Lemullois, A. Aubusson-Fleury, et F. Koll, « Basal body positioning and anchoring in the multiciliated cell Paramecium tetraurelia: roles of OFD1 and VFL3 », Cilia, vol. 6, nᵒ 1, 2017.

  • A. Bersweiler, B. D'Autréaux, H. Mazon, A. Kriznik, G. Belli, A. Delaunay-Moisan, M. B. Toledano, et S. Rahuel-Clermont, « A scaffold protein that chaperones a cysteine-sulfenic acid in H2O2 signaling », Nature Chemical Biology, juin 2017.
    Résumé : In Saccharomyces cerevisiae, Yap1 regulates an H2O2-inducible transcriptional response that controls cellular H2O2 homeostasis. H2O2 activates Yap1 by oxidation through the intermediary of the thiol peroxidase Orp1. Upon reacting with H2O2, Orp1 catalytic cysteine oxidizes to a sulfenic acid, which then engages into either an intermolecular disulfide with Yap1, leading to Yap1 activation, or an intramolecular disulfide that commits the enzyme into its peroxidatic cycle. How the first of these two competing reactions, which is kinetically unfavorable, occurs was previously unknown. We show that the Yap1-binding protein Ybp1 brings together Orp1 and Yap1 into a ternary complex that selectively activates condensation of the Orp1 sulfenylated cysteine with one of the six Yap1 cysteines while inhibiting Orp1 intramolecular disulfide formation. We propose that Ybp1 operates as a scaffold protein and as a sulfenic acid chaperone to provide specificity in the transfer of oxidizing equivalents by a reactive sulfenic acid species.
    Mots-clés : BIOCELL, SOC.

  • K. Bodvard, K. Peeters, F. Roger, N. Romanov, A. Igbaria, N. Welkenhuysen, G. Palais, W. Reiter, M. B. Toledano, M. Käll, et M. Molin, « Light-sensing via hydrogen peroxide and a peroxiredoxin », Nature Communications, vol. 8, p. 14791, mars 2017.

  • S. C. Brown, M. Bourge, N. Maunoury, M. Wong, M. W. Bianchi, S. Lepers-Andrzejewski, P. Besse, S. Siljak-Yakovlev, M. Dron, et B. Satiat-Jeunemaître, « DNA remodelling by Strict Partial Endoreplication in orchids, an original process in the plant kingdom », Genome Biology and Evolution, avr. 2017.
    Résumé : DNA remodelling during endoreplication appears to be a strong developmental characteristic in orchids. In this study, we analysed DNA content and nuclei in 41 species of orchids to further map the genome evolution in this plant family. We demonstrate that the DNA remodelling observed in 36 out of 41 orchids studied corresponds to strict partial endoreplication. Such process is developmentally regulated in each wild species studied. Cytometry data analyses allowed us to propose a model where nuclear states 2C, 4E, 8E, etc. form a series comprising a fixed proportion, the euploid genome 2C, plus 2 to 32 additional copies of a complementary part of the genome. The fixed proportion ranged from 89% of the genome in Vanilla mexicana down to 19% in V. pompona, the lowest value for all 148 orchids reported. Insterspecific hybridisation did not suppress this phenomenon. Interestingly, this process was not observed in mass-produced epiphytes. Nucleolar volumes grow with the number of endocopies present, coherent with high transcription activity in endoreplicated nuclei. Our analyses suggest species-specific chromatin rearrangement. Towards understanding endoreplication, V. planifolia constitutes a tractable system for isolating the genomic sequences that confer an advantage via endoreplication from those that apparently suffice at diploid level.
    Mots-clés : BIOCELL, CYTO, cytogenetics, cytometry, DYNBSJ, endoreplication, genome imbalance, Genome Size, IMAGIF, MINION, PF, PHOT, Vanilla.

  • S. Chardonnet, T. Bessiron, C. I. Ramos, R. Dammak, M. - A. Richard, C. Boursier, C. Cadillac, F. M. Coquelle, S. Bossi, F. Ango, P. Le Maréchal, P. Decottignies, C. Berrier, H. McLean, et H. Daniel, « Native metabotropic glutamate receptor 4 depresses synaptic transmission through an unusual Gαq transduction pathway », Neuropharmacology, avr. 2017.
    Résumé : In cerebellar cortex, mGlu4 receptors located on parallel fibers play an essential role in normal motor function, but the molecular mechanisms involved are not yet completely understood. Using a strategy combining biochemical and electrophysiological approaches in the rodent cerebellum, we demonstrate that presynaptic mGlu4 receptors control synaptic transmission through an atypical activation of Gαq proteins. First, the Gαq subunit, PLC and PKC signaling proteins present in cerebellar extracts are retained on affinity chromatography columns grafted with different sequences of the cytoplasmic domain of mGlu4 receptor. The i2 loop and the C terminal domain were used as baits, two domains that are known to play a pivotal role in coupling selectivity and efficacy. Second, in situ proximity ligation assays show that native mGlu4 receptors and Gαq subunits are in close physical proximity in cerebellar cortical slices. Finally, electrophysiological experiments demonstrate that the molecular mechanisms underlying mGlu4 receptor-mediated inhibition of transmitter release at cerebellar Parallel Fiber (PF) - Molecular Layer Interneuron (MLI) synapses involves the Gαq-PLC signaling pathway. Taken together, our results provide compelling evidence that, in the rodent cerebellar cortex, mGlu4 receptors act by coupling to the Gαq protein and PLC effector system to reduce glutamate synaptic transmission.
    Mots-clés : BIOCELL, Cerebellar cortex, DYNBSJ, G protein, Molecular layer interneurons, Presynaptic metabotropic glutamate receptor 4, Signaling pathway, Synaptic transmission.

  • Y. Chen, V. Scarcelli, et R. Legouis, « Approaches for Studying Autophagy in Caenorhabditis elegans », Cells, vol. 6, nᵒ 3, p. 27, août 2017.
    Mots-clés : aggrephagy, BIOCELL, C. elegans, Electron Microscopy, Genetics, in vivo imaging, LGG-1, LGG-2, mitophagy, OTOFAG.

  • A. Delaunay-Moisan, A. Ponsero, et M. Toledano, « Reexamining the function of glutathione in oxidative protein folding and secretion », Antioxidants & Redox Signaling, août 2017.
    Résumé : SIGNIFICANCE: Disturbance of glutathione metabolism is a hallmark of numerous diseases, yet glutathione functions are poorly understood. One key to this question is to consider its functional compartmentation. In the endoplasmic reticulum (ER), protein folding involves disulfide bond formation catalyzed by the thiol oxidase Ero1 and proteins from the disulfide isomerase family (PDI). GSH competes with substrates for oxidation by Ero1, but its requirement for ER oxidative protein folding is questioned. Recent Advances: Oxidative protein folding has been thoroughly dissected over the last decades, and its actors and their mode of action elucidated. Genetically-encoded GSH probes have recently provided an access to subcellular redox metabolism, including the ER. CRITICAL ISSUES: Of the few often-contradictory models of the role of GSH in the ER, the most popular suggest it serves as reducing power. Yet, as a reductant, GSH also activates Ero1, which questions how glutathione can nevertheless support protein reduction. Hence, whether glutathione operates in the ER as a reductant, an oxidant, or just as a "blank" compound mirroring ER/periplasm redox activity is a highly debated question, further stimulated by the puzzling occurrence of glutathione in the E. coli periplasmic "secretory" compartment, aside of the Dsb thiol-reducing and oxidase pathways. FUTURE DIRECTIONS: Addressing the mechanisms controlling glutathione traffic in and out the ER/periplasm and its recycling will help address glutathione function in secretion. In addition, as thioredoxin reductase was recently implicated in ER oxidative protein folding, the relative contribution of each of these two reducing pathways should now be addressed.
    Mots-clés : BIOCELL, SOC.

  • E. Diatloff, E. S. Mace, D. R. Jordan, S. Filleur, S. Tai, S. Schmidt, et I. D. Godwin, « The vegetative nitrogen response of sorghum lines containing different alleles for nitrate reductase and glutamate synthase », Molecular Breeding, vol. 37, nᵒ 11, 2017.

  • M. J. Domingues, J. Martinez-Sanz, L. Papon, L. Larue, L. Mouawad, et J. Bonaventure, « Structure-based mutational analysis of ICAT residues mediating negative regulation of β-catenin co-transcriptional activity », PloS One, vol. 12, nᵒ 3, p. e0172603, 2017.
    Résumé : ICAT (Inhibitor of β-CAtenin and TCF) is a small acidic protein that negatively regulates β-catenin co-transcriptional activity by competing with TCF/LEF factors in their binding to β-catenin superhelical core. In melanoma cells, ICAT competes with LEF1 to negatively regulate the M-MITF and NEDD9 target genes. The structure of ICAT consists of two domains: the 3-helix bundle N-terminal domain binds to β-catenin Armadillo (Arm) repeats 10-12 and the C-terminal tail binds to Arm repeats 5-9. To elucidate the structural mechanisms governing ICAT/β-catenin interactions in melanoma cells, three ICAT residues Y15, K19 and V22 in the N-terminal domain, contacting hydrophobic β-catenin residue F660, were mutated and interaction was assessed by immunoprecipitation. Despite the moderate hydrophobicity of the contact, its removal completely abolished the interaction. In the ICAT C-terminal tail consensus sequence, neutralization of the electrostatic interactions between residues D66, E75 and β-catenin residues K435, K312, coupled to deletion of the hydrophobic contact between F71 and β-catenin R386, markedly reduced, but failed to abolish the ICAT-mediated negative regulation of M-MITF and NEDD9 promoters. We conclude that in melanoma cells, anchoring of ICAT N-terminal domain to β-catenin through the hook made by residue F660, trapped in the pincers formed by ICAT residues Y15 and V22, is crucial for stabilizing the ICAT/β-catenin complex. This is a prerequisite for binding of the consensus peptide to Arm repeats 5-9 and competition with LEF1. Differences between ICAT and LEF1 in their affinity for β-catenin may rely on the absence in ICAT of hydrophilic residues between D66 and F71.
    Mots-clés : BIOCELL, BIOCIL.

  • G. Dubeaux et G. Vert, « Zooming into plant ubiquitin-mediated endocytosis », Current Opinion in Plant Biology, vol. 40, p. 56-62, juill. 2017.
    Résumé : Endocytosis in plants plays an essential role, not only for basic cellular functions but also for growth, development, and environmental responses. Over the past few years, ubiquitin emerged as a major signal triggering the removal of plasma membrane proteins from the cell surface and promoting their vacuolar targeting. Detailed genetic, biochemical and imaging studies have provided initial insights into the precise mechanisms and roles of ubiquitin-mediated endocytosis in plants. Here, we summarize the present state of knowledge about the machinery involved in plant ubiquitin-mediated endocytosis and how this is coordinated in time and space to control the internalization and the endosomal sorting of endocytosed proteins.
    Mots-clés : BIOCELL, UBINET.

  • C. Eisenach, U. Baetz, N. V. Huck, J. Zhang, A. De Angeli, G. J. M. Beckers, et E. Martinoia, « ABA-Induced Stomatal Closure Involves ALMT4, a Phosphorylation-Dependent Vacuolar Anion Channel of Arabidopsis », The Plant Cell, vol. 29, nᵒ 10, p. 2552-2569, 2017.

  • C. Eisenach et A. De Angeli, « Ion Transport at the Vacuole During Stomatal Movements », Plant Physiology, p. pp.00130.2017, avr. 2017.

  • R. Enrique Gomez, J. Joubès, N. Valentin, H. Batoko, B. Satiat-Jeunemaître, et A. Bernard, « Lipids in membrane dynamics during autophagy in plants », Journal of Experimental Botany, nov. 2017.
    Résumé : Autophagy is a critical pathway for plant adaptation to stress. Macroautophagy relies on the biogenesis of a specialized membrane named the phagophore that maturates into a double membrane vesicle. Proteins and lipids act synergistically to promote membrane structure and functions, yet research on autophagy has mostly focused on autophagy-related proteins while knowledge of supporting lipids in the formation of autophagic membranes remains scarce. This review expands on studies in plants with examples from other organisms to present and discuss our current understanding of lipids in membrane dynamics associated with the autophagy pathway in plants.
    Mots-clés : Arabidopsis, autophagy, BIOCELL, DYNBSJ, homeostasis, lipids, membrane, Plant.

  • A. Glatigny, P. Gambette, A. Bourand-Plantefol, G. Dujardin, et M. - H. Mucchielli-Giorgi, « Development of an in silico method for the identification of subcomplexes involved in the biogenesis of multiprotein complexes in Saccharomyces cerevisiae », BMC systems biology, vol. 11, nᵒ 1, p. 67, juill. 2017.
    Résumé : BACKGROUND: Large sets of protein-protein interaction data coming either from biological experiments or predictive methods are available and can be combined to construct networks from which information about various cell processes can be extracted. We have developed an in silico approach based on these information to model the biogenesis of multiprotein complexes in the yeast Saccharomyces cerevisiae. RESULTS: Firstly, we have built three protein interaction networks by collecting the protein-protein interactions, which involved the subunits of three complexes, from different databases. The protein-protein interactions come from different kinds of biological experiments or are predicted. We have chosen the elongator and the mediator head complexes that are soluble and exhibit an architecture with subcomplexes that could be functional modules, and the mitochondrial bc 1 complex, which is an integral membrane complex and for which a late assembly subcomplex has been described. Secondly, by applying a clustering strategy to these networks, we were able to identify subcomplexes involved in the biogenesis of the complexes as well as the proteins interacting with each subcomplex. Thirdly, in order to validate our in silico results for the cytochrome bc1 complex we have analysed the physical interactions existing between three subunits by performing immunoprecipitation experiments in several genetic context. CONCLUSIONS: For the two soluble complexes (the elongator and mediator head), our model shows a strong clustering of subunits that belong to a known subcomplex or module. For the membrane bc 1 complex, our approach has suggested new interactions between subunits in the early steps of the assembly pathway that were experimentally confirmed. Scripts can be downloaded from the site: .
    Mots-clés : BIM, BIOCELL, BIOMIT, Complex assembly, DBG, Graph clustering, PPI network, Protein complex, Protein-protein interactions, Subcomplex.

  • Y. Goulev, S. Morlot, A. Matifas, B. Huang, M. Molin, M. B. Toledano, et G. Charvin, « Nonlinear feedback drives homeostatic plasticity in H2O2 stress response », eLife, vol. 6, avr. 2017.
    Résumé : Homeostatic systems that rely on genetic regulatory networks are intrinsically limited by the transcriptional response time, which may restrict a cell's ability to adapt to unanticipated environmental challenges. To bypass this limitation, cells have evolved mechanisms whereby exposure to mild stress increases their resistance to subsequent threats. However, the mechanisms responsible for such adaptive homeostasis remain largely unknown. Here, we used live-cell imaging and microfluidics to investigate the adaptive response of budding yeast to temporally controlled H2O2 stress patterns. We demonstrate that acquisition of tolerance is a systems-level property resulting from nonlinearity of H2O2 scavenging by peroxiredoxins and our study reveals that this regulatory scheme induces a striking hormetic effect of extracellular H2O2 stress on replicative longevity. Our study thus provides a novel quantitative framework bridging the molecular architecture of a cellular homeostatic system to the emergence of nonintuitive adaptive properties.
    Mots-clés : BIOCELL, cell biology, Computational Biology, S. cerevisiae, SOC, systems biology.

  • F. Habarou, Y. Hamel, T. B. Haack, R. G. Feichtinger, E. Lebigot, I. Marquardt, K. Busiah, C. Laroche, M. Madrange, C. Grisel, C. Pontoizeau, M. Eisermann, A. Boutron, D. Chrétien, B. Chadefaux-Vekemans, R. Barouki, C. Bole-Feysot, P. Nitschke, N. Goudin, N. Boddaert, I. Nemazanyy, A. Delahodde, S. Kölker, R. J. Rodenburg, G. C. Korenke, T. Meitinger, T. M. Strom, H. Prokisch, A. Rotig, C. Ottolenghi, J. A. Mayr, et P. de Lonlay, « Biallelic Mutations in LIPT2 Cause a Mitochondrial Lipoylation Defect Associated with Severe Neonatal Encephalopathy », American Journal of Human Genetics, vol. 101, nᵒ 2, p. 283-290, août 2017.
    Résumé : Lipoate serves as a cofactor for the glycine cleavage system (GCS) and four 2-oxoacid dehydrogenases functioning in energy metabolism (α-oxoglutarate dehydrogenase [α-KGDHc] and pyruvate dehydrogenase [PDHc]), or amino acid metabolism (branched-chain oxoacid dehydrogenase, 2-oxoadipate dehydrogenase). Mitochondrial lipoate synthesis involves three enzymatic steps catalyzed sequentially by lipoyl(octanoyl) transferase 2 (LIPT2), lipoic acid synthetase (LIAS), and lipoyltransferase 1 (LIPT1). Mutations in LIAS have been associated with nonketotic hyperglycinemia-like early-onset convulsions and encephalopathy combined with a defect in mitochondrial energy metabolism. LIPT1 deficiency spares GCS deficiency and has been associated with a biochemical signature of combined 2-oxoacid dehydrogenase deficiency leading to early death or Leigh-like encephalopathy. We report on the identification of biallelic LIPT2 mutations in three affected individuals from two families with severe neonatal encephalopathy. Brain MRI showed major cortical atrophy with white matter abnormalities and cysts. Plasma glycine was mildly increased. Affected individuals' fibroblasts showed reduced oxygen consumption rates, PDHc, α-KGDHc activities, leucine catabolic flux, and decreased protein lipoylation. A normalization of lipoylation was observed after expression of wild-type LIPT2, arguing for LIPT2 requirement in intramitochondrial lipoate synthesis. Lipoic acid supplementation did not improve clinical condition nor activities of PDHc, α-KGDHc, or leucine metabolism in fibroblasts and was ineffective in yeast deleted for the orthologous LIP2.
    Mots-clés : BIOCELL, encephalopathy, FDMITO, hyperglycinemia, lipoic acid, LIPT2, metabolic flux, pyruvate dehydrogenase, α-oxoglutarate dehydrogenase.

  • C. H. He, D. S. Black, C. M. Allan, B. Meunier, S. Rahman, et C. F. Clarke, « Human COQ9 Rescues a coq9 Yeast Mutant by Enhancing Coenzyme Q Biosynthesis from 4-Hydroxybenzoic Acid and Stabilizing the CoQ-Synthome », Frontiers in Physiology, vol. 8, p. 463, 2017.
    Résumé : Coq9 is required for the stability of a mitochondrial multi-subunit complex, termed the CoQ-synthome, and the deamination step of Q intermediates that derive from para-aminobenzoic acid (pABA) in yeast. In human, mutations in the COQ9 gene cause neonatal-onset primary Q10 deficiency. In this study, we determined whether expression of human COQ9 could complement yeast coq9 point or null mutants. We found that expression of human COQ9 rescues the growth of the temperature-sensitive yeast mutant, coq9-ts19, on a non-fermentable carbon source and increases the content of Q6, by enhancing Q biosynthesis from 4-hydroxybenzoic acid (4HB). To study the mechanism for the rescue by human COQ9, we determined the steady-state levels of yeast Coq polypeptides in the mitochondria of the temperature-sensitive yeast coq9 mutant expressing human COQ9. We show that the expression of human COQ9 significantly increased steady-state levels of yeast Coq4, Coq6, Coq7, and Coq9 at permissive temperature. Human COQ9 polypeptide levels persisted at non-permissive temperature. A small amount of the human COQ9 co-purified with tagged Coq6, Coq6-CNAP, indicating that human COQ9 interacts with the yeast Q-biosynthetic complex. These findings suggest that human COQ9 rescues the yeast coq9 temperature-sensitive mutant by stabilizing the CoQ-synthome and increasing Q biosynthesis from 4HB. This finding provides a powerful approach to studying the function of human COQ9 using yeast as a model.
    Mots-clés : BIOCELL, BIOMIT, coenzyme Q, human homolog, Immunoprecipitation, mitochondrial metabolism, Saccharomyces cerevisiae, temperature-sensitive mutant.

  • C. Jenzer et R. Legouis, « Les multiples facettes de l’autophagie au cours du développement », médecine/sciences, vol. 33, nᵒ 3, p. 238-245, 2017.

  • A. Johnson et G. Vert, « Single Event Resolution of Plant Plasma Membrane Protein Endocytosis by TIRF Microscopy », Frontiers in Plant Science, vol. 8, p. 612, 2017.
    Résumé : Endocytosis is a key process in the internalization of extracellular materials and plasma membrane proteins, such as receptors and transporters, thereby controlling many aspects of cell signaling and cellular homeostasis. Endocytosis in plants has an essential role not only for basic cellular functions but also for growth and development, nutrient delivery, toxin avoidance, and pathogen defense. The precise mechanisms of endocytosis in plants remain quite elusive. The lack of direct visualization and examination of single events of endocytosis has greatly hampered our ability to precisely monitor the cell surface lifetime and the recruitment profile of proteins driving endocytosis or endocytosed cargos in plants. Here, we discuss the necessity to systematically implement total internal reflection fluorescence microcopy (TIRF) in the Plant Cell Biology community and present reliable protocols for high spatial and temporal imaging of endocytosis in plants using clathrin-mediated endocytosis as a test case, since it represents the major route for internalization of cell-surface proteins in plants. We developed a robust method to directly visualize cell surface proteins using TIRF microscopy combined to a high throughput, automated and unbiased analysis pipeline to determine the temporal recruitment profile of proteins to single sites of endocytosis, using the departure of clathrin as a physiological reference for scission. Using this 'departure assay', we assessed the recruitment of two different AP-2 subunits, alpha and mu, to the sites of endocytosis and found that AP2A1 was recruited in concert with clathrin, while AP2M was not. This validated approach therefore offers a powerful solution to better characterize the plant endocytic machinery and the dynamics of one's favorite cargo protein.
    Mots-clés : Arabidopsis, BIOCELL, endocytosis, imaging techniques, plants, TIRF microscopy, trafficking, UBINET.

  • O. Khalimonchuk, M. Bestwick, B. Meunier, T. C. Watts, et D. R. Winge, « Correction for Khalimonchuk et al., "Formation of the Redox Cofactor Centers during Cox1 Maturation in Yeast Cytochrome Oxidase" », Molecular and Cellular Biology, vol. 37, nᵒ 11, juin 2017.

  • I. Kühl, M. Miranda, I. Atanassov, I. Kuznetsova, Y. Hinze, A. Mourier, A. Filipovska, et N. - G. Larsson, « Transcriptomic and proteomic landscape of mitochondrial dysfunction reveals secondary coenzyme Q deficiency in mammals », eLife, vol. 6, nov. 2017.
    Résumé : Dysfunction of the oxidative phosphorylation (OXPHOS) system is a major cause of human disease and the cellular consequences are highly complex. Here, we present comparative analyses of mitochondrial proteomes, cellular transcriptomes and targeted metabolomics of five knockout mouse strains deficient in essential factors required for mitochondrial DNA gene expression, leading to OXPHOS dysfunction. Moreover, we describe sequential protein changes during post-natal development and progressive OXPHOS dysfunction in time course analyses in control mice and a middle lifespan knockout, respectively. Very unexpectedly, we identify a new response pathway to OXPHOS dysfunction in which the intra-mitochondrial synthesis of coenzyme Q (ubiquinone, Q) and Q levels are profoundly decreased, pointing towards novel possibilities for therapy. Our extensive omics analyses provide a high-quality resource of altered gene expression patterns under severe OXPHOS deficiency comparing several mouse models, that will deepen our understanding, open avenues for research and provide an important reference for diagnosis and treatment.
    Mots-clés : BIOCELL, biochemistry, BIOMIT, cell biology, Cellular transcriptome, Coenzyme Q biosynthesis, Mitochondrial gene expression, Mitoproteome, mouse, One-carbon pathway, OXPHOS dysfunction.

  • C. Lefebvre, R. Legouis, et E. Culetto, « ESCRT and autophagies: endosomal functions and beyond », Seminars in Cell & Developmental Biology, août 2017.
    Résumé : ESCRT (endosomal sorting complex required for transport) machinery has been initially identified for its role during endocytosis, which allows membrane proteins and lipids to be degraded in the lysosome. ESCRT function is required to form intraluminal vesicles permitting internalization of cytosolic components or membrane embedded cargoes and promoting endosome maturation. ESCRT machinery also contributes to multiple key cell mechanisms in which it reshapes membranes. In addition, ESCRT actively participates in different types of autophagy processes for degrading cytosolic components, such as endosomal microautophagy and macroautophagy. During macroautophagy, ESCRT promotes formation of multivesicular bodies, which can fuse with autophagosomes to generate amphisomes. This latter fusion probably brings to autophagosomes key membrane molecules necessary for the subsequent fusion with lysosomes. Interestingly, during macroautophagy, ESCRT proteins could be involved in non-canonical functions such as vesicle tethering or phagophore membrane sealing. Additionally, ESCRT subunits could directly interact with key autophagy related proteins to build a closer connection between endocytosis and autophagy pathways.
    Mots-clés : amphisome, ATG, autophagosome, Autophagy, BIOCELL, endosome, ESCRT, OTOFAG.

  • J. Marion, R. Le Bars, B. Satiat-Jeunemaitre, et C. Boulogne, « Optimizing CLEM protocols for plants cells: GMA embedding and cryosections as alternatives for preservation of GFP fluorescence in Arabidopsis roots », Journal of Structural Biology, 2017.
    Mots-clés : Arabidopsis, BIOCELL, Correlative microscopy, DYNBSJ, GFP, GMA resin, IMAGIF, MET, PF, PHOT, Tokuyasu, Transmission electron microscopy.

  • S. Martins, A. Montiel-Jorda, A. Cayrel, S. Huguet, C. P. - L. Roux, K. Ljung, et G. Vert, « Brassinosteroid signaling-dependent root responses to prolonged elevated ambient temperature », Nature Communications, vol. 8, nᵒ 1, p. 309, août 2017.
    Résumé : Due to their sessile nature, plants have to cope with and adjust to their fluctuating environment. Temperature elevation stimulates the growth of Arabidopsis aerial parts. This process is mediated by increased biosynthesis of the growth-promoting hormone auxin. How plant roots respond to elevated ambient temperature is however still elusive. Here we present strong evidence that temperature elevation impinges on brassinosteroid hormone signaling to alter root growth. We show that elevated temperature leads to increased root elongation, independently of auxin or factors known to drive temperature-mediated shoot growth. We further demonstrate that brassinosteroid signaling regulates root responses to elevated ambient temperature. Increased growth temperature specifically impacts on the level of the brassinosteroid receptor BRI1 to downregulate brassinosteroid signaling and mediate root elongation. Our results establish that BRI1 integrates temperature and brassinosteroid signaling to regulate root growth upon long-term changes in environmental conditions associated with global warming.Moderate heat stimulates the growth of Arabidopsis shoots in an auxin-dependent manner. Here, Martins et al. show that elevated ambient temperature modifies root growth by reducing the BRI1 brassinosteroid-receptor protein level and downregulating brassinosteroid signaling.
    Mots-clés : BIOCELL, UBINET.

  • S. Martins, G. Vert, et Y. Jaillais, « Probing Activation and Deactivation of the BRASSINOSTEROID INSENSITIVE1 Receptor Kinase by Immunoprecipitation », Methods in Molecular Biology (Clifton, N.J.), vol. 1564, p. 169-180, 2017.
    Résumé : Brassinosteroids (BRs) are sterol-derived hormones that control plant growth and development. The BR receptor complex is encoded by the BRASSINOSTEROID INSENSITIVE1 (BRI1) and members of the SOMATIC EMBRYOGENESIS RECEPTOR KINASE family. For activation and deactivation, the BR receptor complex uses different posttranslational modifications and recruits various partner proteins. Here, we describe optimized immunoprecipitation protocols and variants for biochemical analyses of posttranslational modifications of BRI1 and of protein-protein interactions.
    Mots-clés : BIOCELL, Brassinosteroids, BRI1, Immunoprecipitation, Phosphorylation, Protein–protein interaction, UBINET, Ubiquitination.

  • D. Molino, A. C. Nascimbeni, F. Giordano, P. Codogno, et E. Morel, « ER-driven membrane contact sites: Evolutionary conserved machineries for stress response and autophagy regulation? », Communicative & Integrative Biology, vol. 10, nᵒ 5-6, p. e1401699, 2017.
    Résumé : Endoplasmic Reticulum (ER), spreading in the whole cell cytoplasm, is a central player in eukaryotic cell homeostasis, from plants to mammals. Beside crucial functions, such as membrane lipids and proteins synthesis and outward transport, the ER is able to connect to virtually every endomembrane compartment by specific tethering molecular machineries, which enables the establishment of membrane-membrane contact sites. ER-mitochondria contact sites have been shown to be involved in autophagosome biogenesis, the main organelle of the autophagy degradation pathway. More recently we demonstrated that also ER-plasma membrane contact sites are sites for autophagosomes assembly, suggesting that more generally ER-organelles contacts are involved in autophagy and organelle biogenesis. Here we aim to discuss the functioning of ER-driven contact sites in mammals and plants and more in particular emphasize on their recently highlighted function in autophagy to finally conclude on some key questions that may be useful for further research in the field.
    Mots-clés : autophagosome, BIOCELL, COAST, contact-sites, ER membrane dynamics, mitochondria, plasma membrane.

  • C. Panozzo, A. Laleve, D. Tribouillard-Tanvier, J. Ostojić, C. Sellem, G. Friocourt, A. Bourand-Plantefol, A. Burg, A. Delahodde, M. Blondel, et G. Dujardin, « Chemicals or mutations that target mitochondrial translation can rescue the respiratory deficiency of yeast bcs1 mutants », Biochimica Et Biophysica Acta, sept. 2017.
    Résumé : Bcs1p is a chaperone that is required for the incorporation of the Rieske subunit within complex III of the mitochondrial respiratory chain. Mutations in the human gene BCS1L (BCS1-like) are the most frequent nuclear mutations resulting in complex III-related pathologies. In yeast, the mimicking of some pathogenic mutations causes a respiratory deficiency. We have screened chemical libraries and found that two antibiotics, pentamidine and clarithromycin, can compensate two bcs1 point mutations in yeast, one of which is the equivalent of a mutation found in a human patient. As both antibiotics target the large mtrRNA of the mitoribosome, we focused our analysis on mitochondrial translation. We found that the absence of non-essential translation factors Rrf1 or Mif3, which act at the recycling/initiation steps, also compensates for the respiratory deficiency of yeast bcs1 mutations. At compensating concentrations, both antibiotics, as well as the absence of Rrf1, cause an imbalanced synthesis of respiratory subunits which impairs the assembly of the respiratory complexes and especially that of complex IV. Finally, we show that pentamidine also decreases the assembly of complex I in nematode mitochondria. It is well known that complexes III and IV exist within the mitochondrial inner membrane as supramolecular complexes III2/IV in yeast or I/III2/IV in higher eukaryotes. Therefore, we propose that the changes in mitochondrial translation caused by the drugs or by the absence of translation factors, can compensate for bcs1 mutations by modifying the equilibrium between illegitimate, and thus inactive, and active supercomplexes.
    Mots-clés : Antibiotics, Bcs1 protein, BIOCELL, BIOMIT, FDMITO, mitochondria, Respiratory chain, translation, Yeast.

  • A. Paul, A. Drecourt, F. Petit, D. D. Deguine, C. Vasnier, M. Oufadem, C. Masson, C. Bonnet, S. Masmoudi, I. Mosnier, L. Mahieu, D. Bouccara, J. Kaplan, G. Challe, C. Domange, F. Mochel, O. Sterkers, S. Gerber, P. Nitschke, C. Bole-Feysot, L. Jonard, S. Gherbi, O. Mercati, I. Ben Aissa, S. Lyonnet, A. Rötig, A. Delahodde, et S. Marlin, « FDXR Mutations Cause Sensorial Neuropathies and Expand the Spectrum of Mitochondrial Fe-S-Synthesis Diseases », American Journal of Human Genetics, sept. 2017.
    Résumé : Hearing loss and visual impairment in childhood have mostly genetic origins, some of them being related to sensorial neuronal defects. Here, we report on eight subjects from four independent families affected by auditory neuropathy and optic atrophy. Whole-exome sequencing revealed biallelic mutations in FDXR in affected subjects of each family. FDXR encodes the mitochondrial ferredoxin reductase, the sole human ferredoxin reductase implicated in the biosynthesis of iron-sulfur clusters (ISCs) and in heme formation. ISC proteins are involved in enzymatic catalysis, gene expression, and DNA replication and repair. We observed deregulated iron homeostasis in FDXR mutant fibroblasts and indirect evidence of mitochondrial iron overload. Functional complementation in a yeast strain in which ARH1, the human FDXR ortholog, was deleted established the pathogenicity of these mutations. These data highlight the wide clinical heterogeneity of mitochondrial disorders related to ISC synthesis.
    Mots-clés : ARH1, Auditory neuropathy, BIOCELL, FDMITO, FDXR, Fe-S cluster synthesis, iron overload, iron-sulfur cluster, mitochondria, optic atrophy.

  • P. Pétriacq, L. de Bont, L. Genestout, J. Hao, C. Laureau, I. Florez-Sarasa, T. Rzigui, G. Queval, F. Gilard, C. Mauve, F. Guérard, M. Lamothe-Sibold, J. Marion, C. Fresneau, S. Brown, A. Danon, A. Krieger-Liszkay, R. Berthomé, M. Ribas-Carbo, G. Tcherkez, G. Cornic, B. Pineau, B. Gakière, et R. De Paepe, « Photoperiod Affects the Phenotype of Mitochondrial Complex I Mutants », Plant Physiology, vol. 173, nᵒ 1, p. 434-455, 2017.

  • A. J. Ponsero, A. Igbaria, M. A. Darch, S. Miled, C. E. Outten, J. R. Winther, G. Palais, B. D'Autréaux, A. Delaunay-Moisan, et M. B. Toledano, « Endoplasmic Reticulum Transport of Glutathione by Sec61 Is Regulated by Ero1 and Bip », Molecular Cell, sept. 2017.
    Résumé : In the endoplasmic reticulum (ER), Ero1 catalyzes disulfide bond formation and promotes glutathione (GSH) oxidation to GSSG. Since GSSG cannot be reduced in the ER, maintenance of the ER glutathione redox state and levels likely depends on ER glutathione import and GSSG export. We used quantitative GSH and GSSG biosensors to monitor glutathione import into the ER of yeast cells. We found that glutathione enters the ER by facilitated diffusion through the Sec61 protein-conducting channel, while oxidized Bip (Kar2) inhibits transport. Increased ER glutathione import triggers H2O2-dependent Bip oxidation through Ero1 reductive activation, which inhibits glutathione import in a negative regulatory loop. During ER stress, transport is activated by UPR-dependent Ero1 induction, and cytosolic glutathione levels increase. Thus, the ER redox poise is tuned by reciprocal control of glutathione import and Ero1 activation. The ER protein-conducting channel is permeable to small molecules, provided the driving force of a concentration gradient.
    Mots-clés : BIOCELL, Bip, disulfide bond, Endoplasmic Reticulum, Ero1, Glutathione, membrane transport, oxidative protein folding, redox biosensor, Redox homeostasis, Sec61, SOC.

  • P. Richards, S. Ourabah, J. Montagne, A. - F. Burnol, C. Postic, et S. Guilmeau, « MondoA/ChREBP: The usual suspects of transcriptional glucose sensing; Implication in pathophysiology », Metabolism: Clinical and Experimental, vol. 70, p. 133-151, mai 2017.
    Résumé : Identification of the Mondo glucose-responsive transcription factors family, including the MondoA and MondoB/ChREBP paralogs, has shed light on the mechanism whereby glucose affects gene transcription. They have clearly emerged, in recent years, as key mediators of glucose sensing by multiple cell types. MondoA and ChREBP have overlapping yet distinct expression profiles, which underlie their downstream targets and separate roles in regulating genes involved in glucose metabolism. MondoA can restrict glucose uptake and influences energy utilization in skeletal muscle, while ChREBP signals energy storage through de novo lipogenesis in liver and white adipose tissue. Because Mondo proteins mediate metabolic adaptations to changing glucose levels, a better understanding of cellular glucose sensing through Mondo proteins will likely uncover new therapeutic opportunities in the context of the imbalanced glucose homeostasis that accompanies metabolic diseases such as type 2 diabetes and cancer. Here, we provide an overview of structural homologies, transcriptional partners as well as the nutrient and hormonal mechanisms underlying Mondo proteins regulation. We next summarize their relative contribution to energy metabolism changes in physiological states and the evolutionary conservation of these pathways. Finally, we discuss their possible targeting in human pathologies.
    Mots-clés : BIOCELL, cancer, ChREBP, Diabetes, Glucose and lipid metabolism, METABO, MondoA.

  • C. Stringari, L. Abdeladim, G. Malkinson, P. Mahou, X. Solinas, I. Lamarre, S. Brizion, J. - B. Galey, W. Supatto, R. Legouis, A. - M. Pena, et E. Beaurepaire, « Multicolor two-photon imaging of endogenous fluorophores in living tissues by wavelength mixing », Scientific Reports, vol. 7, nᵒ 1, p. 3792, juin 2017.
    Résumé : Two-photon imaging of endogenous fluorescence can provide physiological and metabolic information from intact tissues. However, simultaneous imaging of multiple intrinsic fluorophores, such as nicotinamide adenine dinucleotide(phosphate) (NAD(P)H), flavin adenine dinucleotide (FAD) and retinoids in living systems is generally hampered by sequential multi-wavelength excitation resulting in motion artifacts. Here, we report on efficient and simultaneous multicolor two-photon excitation of endogenous fluorophores with absorption spectra spanning the 750-1040 nm range, using wavelength mixing. By using two synchronized pulse trains at 760 and 1041 nm, an additional equivalent two-photon excitation wavelength at 879 nm is generated, and achieves simultaneous excitation of blue, green and red intrinsic fluorophores. This method permits an efficient simultaneous imaging of the metabolic coenzymes NADH and FAD to be implemented with perfect image co-registration, overcoming the difficulties associated with differences in absorption spectra and disparity in concentration. We demonstrate ratiometric redox imaging free of motion artifacts and simultaneous two-photon fluorescence lifetime imaging (FLIM) of NADH and FAD in living tissues. The lifetime gradients of NADH and FAD associated with different cellular metabolic and differentiation states in reconstructed human skin and in the germline of live C. Elegans are thus simultaneously measured. Finally, we present multicolor imaging of endogenous fluorophores and second harmonic generation (SHG) signals during the early stages of Zebrafish embryo development, evidencing fluorescence spectral changes associated with development.
    Mots-clés : BIOCELL, OTOFAG.

  • F. Thomas, C. Jacqueline, T. Tissot, M. Henard, S. Blanchet, G. Loot, E. Dawson, F. Mery, F. Renaud, J. Montagne, C. Beckmann, P. A. Biro, R. Hamede, et B. Ujvari, « The importance of cancer cells for animal evolutionary ecology », Nature Ecology & Evolution, vol. 1, nᵒ 11, p. 1592-1595, nov. 2017.

  • F. Thomas, S. Rome, F. Mery, E. Dawson, J. Montagne, P. A. Biro, C. Beckmann, F. Renaud, R. Poulin, M. Raymond, et B. Ujvari, « Changes in diet associated with cancer: An evolutionary perspective », Evolutionary Applications, vol. 10, nᵒ 7, p. 651-657, août 2017.
    Résumé : Changes in diet are frequently correlated with the occurrence and progression of malignant tumors (i.e., cancer) in both humans and other animals, but an integrated conceptual framework to interpret these changes still needs to be developed. Our aim is to provide a new perspective on dietary changes in tumor-bearing individuals by adapting concepts from parasitology. Dietary changes may occur alongside tumor progression for several reasons: (i) as a pathological side effect with no adaptive value, (ii) as the result of self-medication by the host to eradicate the tumor and/or to slow down its progression, (iii) as a result of host manipulation by the tumor that benefits its progression, and finally (iv) as a host tolerance strategy, to alleviate and repair damages caused by tumor progression. Surprisingly, this tolerance strategy can be beneficial for the host even if diet changes are beneficial to tumor progression, provided that cancer-induced death occurs sufficiently late (i.e., when natural selection is weak). We argue that more data and a unifying evolutionary framework, especially during the early stages of tumorigenesis, are needed to understand the links between changes in diet and tumor progression. We argue that a focus on dietary changes accompanying tumor progression can offer novel preventive and therapeutic strategies against cancer.
    Mots-clés : BIOCELL, malignant cells, manipulation, METABO, nutrition, self‐medication, resistance, tolerance.

  • M. B. Toledano et M. - E. Huang, « The Unfinished Puzzle of Glutathione Physiological Functions, an Old Molecule That Still Retains Many Enigmas », Antioxidants & Redox Signaling, vol. 27, nᵒ 15, p. 1127-1129, nov. 2017.
    Résumé : Glutathione (GSH) is the most abundant nonprotein thiol found in living organisms. Since its discovery 130 years ago, understanding its cellular functions has been the subject of intensive research. Common scientific knowledge states that GSH is a major nonenzymatic antioxidant and redox buffer. Recent approaches that consider GSH compartmentation in the eukaryotic cell challenge this traditional view and reveal novel unexpected insights into GSH metabolism and physiology. This Forum on GSH features six review articles that focus on GSH metabolism and functions in mitochondria and the endoplasmic reticulum; its connection to cellular iron homeostasis, carcinogenesis, and anticancer drug resistance; a revisited view of GSH degradation pathways; and reconsiders old concepts of its mode of action by highlighting the importance of kinetics over thermodynamic redox equilibria. Antioxid. Redox Signal. 27, 1127-1129.
    Mots-clés : BIOCELL, cancer, Drug Resistance, Glutathione, glutathione compartmentalization, glutathione degradation, iron homeostasis, SOC.

  • A. Y. Torres, M. Malartre, A. - M. Pret, et F. Agnès, « JAK/STAT signaling is necessary for cell monosis prior to epithelial cell apoptotic extrusion », Cell Death & Disease, vol. 8, nᵒ 5, p. e2814, mai 2017.
    Résumé : Epithelial cell extrusion is crucial for proper development and tissue homeostasis. High-resolution 3D reconstruction and 4D imaging, combined with genetic analyis, have allowed us to reveal the highly-sterotyped morphogenetic events controlled by JAK/STAT signaling in a developmentally-programmed case of epithelial cell extrusion. Specialized somatic cells, Polar Cells (PCs), are produced in excess and then undergo apoptotic elimination from the follicular epithelium in the Drosophila ovary. We show that supernumerary PCs are first systematically enveloped by PC neighbors on all sides, first laterally, then apically in conjunction with highly-reinforced adherens junctions, and finally basally. The PC to be removed thus loses all contact with follicle cells, germline cells and the basement membrane in a process we have called cell 'monosis', for 'isolation' in Greek. PC monosis takes several hours, and always precedes, and is independent of, activation of apoptosis. JAK/STAT signaling is necessary within the surrounding follicular epithelium for PC monosis. Minutes after monosis is complete, PC apoptotic corpses are formed and extruded laterally within the epithelium, in contrast to the apical and basal extrusions described to date. These apoptotic corpses are engulfed and eliminated by surrounding follicle cells, which are thus acting as non-professional phagocytes. This study therefore shows the non cell-autonomous impact of an epithelium, via JAK/STAT signaling activation, on cell morphogenesis events leading to apoptotic extrusion. It is likely that the use of high-resolution 3D and 4D imaging, which allows for better spatio-temporal understanding of morphogenetic events, will reveal that cell monosis and lateral extrusion within an epithelium are pertinent for other cases of epithelial cell extrusion as well.
    Mots-clés : BIOCELL, SIGDEV.

  • D. Tran, R. Galletti, E. D. Neumann, A. Dubois, R. Sharif-Naeini, A. Geitmann, J. - M. Frachisse, O. Hamant, et G. C. Ingram, « A mechanosensitive Ca(2+) channel activity is dependent on the developmental regulator DEK1 », Nature Communications, vol. 8, nᵒ 1, p. 1009, oct. 2017.
    Résumé : Responses of cells to mechanical stress are thought to be critical in coordinating growth and development. Consistent with this idea, mechanically activated channels play important roles in animal development. For example, the PIEZO1 channel controls cell division and epithelial-layer integrity and is necessary for vascular development in mammals. In plants, the actual contribution of mechanoperception to development remains questionable because very few putative mechanosensors have been identified and the phenotypes of the corresponding mutants are rather mild. Here, we show that the Arabidopsis Defective Kernel 1 (DEK1) protein, which is essential for development beyond early embryogenesis, is associated with a mechanically activated Ca(2+) current in planta, suggesting that perception of mechanical stress plays a critical role in plant development.
    Mots-clés : BIOCELL, MINION.

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