Encontrado(s) 2198266 resultado(s)
Encontrada(s) 219827 página(s)

Purification and characterisation of the fission yeast Ndc80 complex

  • Matsuo, Yuzy
  • Maurer, Sebastian
  • Surrey, Thomas
  • Toda, Takashi
The Ndc80 complex is a conserved outer kinetochore protein complex consisting of Ndc80 (Hec1), Nuf2, Spc24 and Spc25. This complex comprises a major, if not the sole, platform with which the plus ends of the spindle microtubules directly interact. In fission yeast, several studies indicate that multiple microtubule-associated proteins including the Dis1/chTOG microtubule polymerase and the Mal3/EB1 microtubule plus-end tracking protein directly or indirectly bind Ndc80, thereby ensuring stable kinetochore-microtubule attachment. However, the purification of the Ndc80 complex from this yeast has not been achieved, which hampers the in-depth investigation as to how the outer kinetochore attaches to the plus end of the spindle microtubule. Here we report the two-step purification of the fission yeast Ndc80 holo complex from bacteria. First, we purified separately two sub-complexes consisting of Ndc80-Nuf2 and Spc24-Spc25. Then, these two sub-complexes were mixed and applied to size-exclusion chromatography. The reconstituted Ndc80 holo complex is composed of four subunits with equal stoichiometry. The complex possesses microtubule-binding activity, and Total Internal Reflection Fluorescence (TIRF)-microscopy assays show that the complex binds the microtubule lattice. Interestingly, unlike the human complex, the fission yeast complex does not track depolymerising microtubule ends. Further analysis shows that under physiological ionic conditions, the Ndc80 holo complex does not detectably bind Dis1, but instead it interacts with Mal3/EB1, by which the Ndc80 complex tracks the growing microtubule plus end. This result substantiates the notion that the Ndc80 complex plays a crucial role in establishment of the dynamic kinetochore-microtubule interface by cooperating with chTOG and EB1.

Lingüística catalana : noticies de les publicacions del 2000

  • Lorente, Mercè
Tornem a treure el cap en aquestes pàgines per presentar-vos una breu revisió de les publicacions relacionades amb la llengua i la lingüística catalanes, que el món editorial ens va oferir al llarg de l'any 2000.

Protein aggregation into insoluble deposits protects from oxidative stress

  • Carija, Anita
  • Navarro, Susanna
  • Sanchez de Groot, Natalia
  • Ventura, Salvador
Protein misfolding and aggregation have been associated with the onset of neurodegenerative disorders. Recent studies demonstrate that the aggregation process can result in a high diversity of protein conformational states, however the identity of the specific species responsible for the cellular damage is still unclear. Here, we use yeast as a model to systematically analyse the intracellular effect of expressing 21 variants of the amyloid-ß-peptide, engineered to cover a continuous range of intrinsic aggregation propensities. We demonstrate the existence of a striking negative correlation between the aggregation propensity of a given variant and the oxidative stress it elicits. Interestingly, each variant generates a specific distribution of protein assemblies in the cell. This allowed us to identify the aggregated species that remain diffusely distributed in the cytosol and are unable to coalesce into large protein inclusions as those causing the highest levels of oxidative damage. Overall, our results indicate that the formation of large insoluble aggregates may act as a protective mechanism to avoid cellular oxidative stress., We thank Cristina Visentin for help with H2O2 and catalase measurements. This work was funded by the Spanish Ministry of Economy and Competitiveness (BFU2013-44763-P and BIO2016-783-78310-R to S.V.). S.V. has been granted an ICREA ACADEMIA award.

Reduced expression of Paternally Expressed Gene-3 enhances somatic cell reprogramming through mitochondrial activity perturbation

  • Theka, Ilda, 1984-
  • Sottile, Francesco, 1988-
  • Aulicino, Francesco, 1987-
  • García, Álvaro Castells
  • Cosma, Maria Pia, 1970-
Imprinted genes control several cellular and metabolic processes in embryonic and adult tissues. In particular, paternally expressed gene-3 (Peg3) is active in the adult stem cell population and during muscle and neuronal lineage development. Here we have investigated the role of Peg3 in mouse embryonic stem cells (ESCs) and during the process of somatic cell reprogramming towards pluripotency. Our data show that Peg3 knockdown increases expression of pluripotency genes in ESCs and enhances reprogramming efficiency of both mouse embryonic fibroblasts and neural stem cells. Interestingly, we observed that altered activity of Peg3 correlates with major perturbations of mitochondrial gene expression and mitochondrial function, which drive metabolic changes during somatic cell reprogramming. Overall, our study shows that Peg3 is a regulator of pluripotent stem cells and somatic cell reprogramming., We thank Marie Victoire Neguembor, Martina Pesaresi and Sergi Angel Bonilla Pons for suggestions on the manuscript and Umberto Di Vicino for technical support. We thank Angelique di Domenico and the group of Antonella Consiglio for providing us the OPA1, DRP1 and VDAC1 antibodies. We thank Mari Carmen Ortells and the group of Bill Keyes for providing us the OXPHOS antibody. The pInducer10-mir-RUP-PheS plasmid was a gift from Stephen Elledge (Addgene plasmid # 44011). We are grateful for support from Ministerio de Economia y Competitividad and FEDER funds (SAF2011-28580, BFU2014-54717-P, and BFU2015-71984-ERC to M.P.C.), Secretaria d'Universitats i Recerca del Departament d'Economia i Coneixement de la Generalitat de Catalunya (2014 SGR1137 to M.P.C.), the European Union's Horizon 2020 research and innovation programme under grant agreement CellViewer No 686637 (to M.P.C.), Spanish Ministry of Economy and Competitiveness, 'Centro de Excelencia Severo Ochoa 2013-2017 and the CERCA Programme/Generalitat de Catalunya (to M.P.C.), People Programme Marie Curie Actions of the European Union's Seventh Framework Programme (FP7/2007-2013/, n° 290123 to I.T.), La Caixa international PhD fellowship (to F.S.), Ministerio de Ciencia e Innovació FPI (to F.A.) and Ministerio de Ciencia e Innovación FPI-Severo Ochoa (to A.C.G).

Characterization of soft amyloid cores in human prion-like proteins

  • Batlle, Cristina
  • Sanchez de Groot, Natalia
  • Iglesias, Valentin
  • Navarro, Susanna
  • Ventura, Salvador
Prion-like behaviour is attracting much attention due to the growing evidences that amyloid-like self-assembly may reach beyond neurodegeneration and be a conserved functional mechanism. The best characterized functional prions correspond to a subset of yeast proteins involved in translation or transcription. Their conformational promiscuity is encoded in Prion Forming Domains (PFDs), usually long and intrinsically disordered protein segments of low complexity. The compositional bias of these regions seems to be important for the transition between soluble and amyloid-like states. We have proposed that the presence of cryptic soft amyloid cores embedded in yeast PFDs can also be important for their assembly and demonstrated their existence and self-propagating abilities. Here, we used an orthogonal approach in the search of human domains that share yeast PFDs compositional bias and exhibit a predicted nucleating core, identifying 535 prion-like candidates. We selected seven proteins involved in transcriptional or translational regulation and associated to disease to characterize the properties of their amyloid cores. All of them self-assemble spontaneously into amyloid-like structures able to propagate their polymeric state. This provides support for the presence of short sequences able to trigger conformational conversion in prion-like human proteins, potentially regulating their functionality., This work was funded supported by the Spanish Ministry of Economy and Competitiveness [BIO2016-783-78310-R to S.V] and by ICREA [ICREA-Academia 2015 to S.V.]

Evaluation of single-cell genomics to address evolutionary questions using three SAGs of the choanoflagellate Monosiga brevicollis

  • López Escardó, David, 1988-
  • Grau Bové, Xavier
  • Guillaumet-Adkins, Amy
  • Gut, Marta
  • Sieracki, Michael E.
  • Ruiz-Trillo, Iñaki
Single-cell genomics (SCG) appeared as a powerful technique to get genomic information from uncultured organisms. However, SCG techniques suffer from biases at the whole genome amplification step that can lead to extremely variable numbers of genome recovery (5-100%). Thus, it is unclear how useful can SCG be to address evolutionary questions on uncultured microbial eukaryotes. To provide some insights into this, we here analysed 3 single-cell amplified genomes (SAGs) of the choanoflagellate Monosiga brevicollis, whose genome is known. Our results show that each SAG has a different, independent bias, yielding different levels of genome recovery for each cell (6-36%). Genes often appear fragmented and are split into more genes during annotation. Thus, analyses of gene gain and losses, gene architectures, synteny and other genomic features can not be addressed with a single SAG. However, the recovery of phylogenetically-informative protein domains can be up to 55%. This means SAG data can be used to perform accurate phylogenomic analyses. Finally, we also confirm that the co-assembly of several SAGs improves the general genomic recovery. Overall, our data show that, besides important current limitations, SAGs can still provide interesting and novel insights from poorly-known, uncultured organisms., We acknowledge support by ICREA, a European Research Council Consolidator (ERC-2012-Co-616960) grant, and grant (BFU2014-57779-P) from Ministerio de Economía y Competitividad (MINECO) with FEDER funds. We also acknowledge financial support from Secretaria d'Universitats i Recerca del Departament d'Economia i Coneixement de la Generalitat de Catalunya (Project 2014 SGR 619). The authors want to acknowledge Jean-Francois Mangot for the support on the tetranucleotide frequency calculations and Ramon Massana for helpful discussions on the manuscript. We also thank Javier del Campo for some initial ideas, further discussions, and help in the experimental design. Any opinion, findings, and conclusions or recommendations expressed in this material are those of the author(s) and do not necessarily reflect the views of the National Science Foundation. We also thank the commitment of the following people and sponsors: CNRS (in particular Groupement de Recherche GDR3280), European Molecular Biology Laboratory (EMBL), Genoscope/CEAthe French Government 'Investissements d'Avenir' programmes OCEANOMICS (ANR-11-BTBR-0008) and FRANCE GENOMIQUE (ANR-10-INBS-09-08), Agence Nationale de la Recherche, and European Union FP7 (MicroB3/No.287589), We also thank the support and commitment of Agnès B. and Etienne Bourgois, the Veolia Environment Foundation, Region Bretagne, Lorient Agglomeration, World Courier, Illumina, the Eléctricité de France (EDF) Foundation, Fondation pour la recherche sur la biodiversité (FRB), the Foundation Prince Albert II de Monaco, the Tara Foundation, its schooner and teams. We thank MERCATOR-CORIOLIS and ACRI-ST for providing daily satellite data during the expedition. We are also grateful to the French Ministry of Foreign Affairs for supporting the expedition and to the countries who graciously granted sampling permissions. Tara Oceans would not exist without continuous support from 23 institutes (http://oceans.taraexpeditions.org/en/m/science/labs-involved/).

Folksonomy-based tag recommendation for collaborative tagging systems

  • Font Corbera, Frederic
  • Serrà Julià, Joan
  • Serra, Xavier
Collaborative tagging has emerged as a common solution for labelling and organising online digital content. However, collaborative tagging systems typically suffer from a number of issues such as tag scarcity or ambiguous labelling. As a result, the organisation and browsing of tagged content is far from being optimal. In this work the authors present a general scheme for building a folksonomy-based tag recommendation system to help users tagging online content resources. Based on this general scheme, the authorse describe eight tag recommendation methods and extensively evaluate them with data coming from two real-world large-scale datasets of tagged images and sound clips. Their results show that the proposed methods can effectively recommend relevant tags, given a set of input tags and tag co-occurrence information. Moreover, the authors show how novel strategies for selecting the appropriate number of tags to be recommended can significantly improve methods performances. Approaches such as the one presented here can be useful to obtain more comprehensive and coherent descriptions of tagged resources, thus allowing a better organisation, browsing and reuse of online content. Moreover, they can increase the value of folksonomies as reliable sources for knowledge-mining., This work is partially supported under BES2010-037309 FPI grant from the Spanish Ministry of Science and Innovation for the TIN2009-14247-C02-01 DRIMS project. JS acknowledges 2009-SGR-1434 from Generalitat de Catalunya, JAEDOC069/2010 from Consejo Superior de Investigaciones Cientificas, and FP7-ICT-2011-8-318770 from the European Commission.

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