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Boselli, Monica,Lee, Byung-Hoon,Robert, Jessica,Prado, Miguel A.,Min, Sang-Won,Cheng, Chialin,Silva, M. Catarina,Seong, Changhyun,Elsasser, Suzanne,Hatle, Ketki M.,Gahman, Timothy C.,Gygi, Steven P.,H American Society for Biochemistry and Molecular Bi 2017 The Journal of biological chemistry Vol.292 No.47
<P>The ubiquitin-proteasome system (UPS) is responsible for most selective protein degradation in eukaryotes and regulates numerous cellular processes, including cell cycle control and protein quality control. A component of this system, the deubiquitinating enzyme USP14, associates with the proteasome where it can rescue substrates from degradation by removal of the ubiquitin tag. We previously found that a small-molecule inhibitor of USP14, known as IU1, can increase the rate of degradation of a subset of proteasome substrates. We report here the synthesis and characterization of 87 variants of IU1, which resulted in the identification of a 10-fold more potent USP14 inhibitor that retains specificity for USP14. The capacity of this compound, IU1-47, to enhance protein degradation in cells was tested using as a reporter the microtubule-associated protein tau, which has been implicated in many neurodegenerative diseases. Using primary neuronal cultures, IU1-47 was found to accelerate the rate of degradation of wild-type tau, the pathological tau mutants P301L and P301S, and the A152T tau variant. We also report that a specific residue in tau, lysine 174, is critical for the IU1-47–mediated tau degradation by the proteasome. Finally, we show that IU1-47 stimulates autophagic flux in primary neurons. In summary, these findings provide a powerful research tool for investigating the complex biology of USP14.</P>
Toloba, E.,Guhathakurta, P.,Peletier, R. F.,Boselli, A.,Lisker, T.,Falcó,n-Barroso, J.,Simon, J. D.,van de Ven, G.,Paudel, S.,Emsellem, E.,Janz, J.,den Brok, M.,Gorgas, J.,Hensler, G.,Laurikaine IOP Publishing 2014 The Astrophysical journal Supplement series Vol.215 No.2
<P>We present spatially resolved kinematics and global stellar populations and mass-to-light ratios for a sample of 39 dwarf early-type (dE) galaxies in the Virgo cluster studied as part of the SMAKCED stellar absorption-line spectroscopy and imaging survey. This sample is representative of the early-type population in the Virgo cluster in the absolute magnitude range -19.0 < M-r < -16.0 and of all morphological subclasses found in this galaxy population. For each dE, we measure the rotation curve and velocity dispersion profile and fit an analytic function to the rotation curve. We study the significance of the departure of the rotation curve from the best-fit analytic function (poorly fit) and of the difference between the approaching and receding sides of the rotation curve (asymmetry). Our sample includes two dEs with kinematically decoupled cores that have been previously reported. We find that 62 +/- 8% (23 out of the 39) of the dEs have a significant anomaly in their rotation curve. Analysis of the images reveals photometric anomalies for most galaxies. However, there is no clear correlation between the significance of the photometric and kinematic anomalies. We measure age-sensitive (H-beta and H-gamma A) and metallicity sensitive (Fe4668 and Mgb) Lick spectral indices in the LIS-5 angstrom system. This population of galaxies exhibits a wide range of ages and metallicities; we also find that 4 dEs show clear evidence of emission partially filling in the Balmer absorption lines. Finally, we estimate the total masses and dark matter fractions of the dEs and plot them in the mass-size, themass-velocity dispersion, and the fundamental plane scaling relations. The dEs seem to be the bridge between massive early-type galaxies and dSphs, and have a median total mass within the R-e of logM(e) = 9.1 +/- 0.2 and a median dark matter fraction within the R-e of f(DM) = 46 +/- 18%. Any formation model for the dE galaxy class must account for this diversity of kinematic and photometric anomalies and stellar populations.</P>
Suppression of star formation in early-type galaxies by feedback from supermassive black holes
Schawinski, Kevin,Khochfar, Sadegh,Kaviraj, Sugata,Yi, Sukyoung K.,Boselli, Alessandro,Barlow, Tom,Conrow, Tim,Forster, Karl,Friedman, Peter G.,Martin, D. Chris,Morrissey, Patrick,Neff, Susan,Schimino Nature Publishing Group 2006 Nature Vol.442 No.7105
Detailed high-resolution observations of the innermost regions of nearby galaxies have revealed the presence of supermassive black holes. These black holes may interact with their host galaxies by means of ‘feedback’ in the form of energy and material jets; this feedback affects the evolution of the host and gives rise to observed relations between the black hole and the host. Here we report observations of the ultraviolet emissions of massive early-type galaxies. We derive an empirical relation for a critical black-hole mass (as a function of velocity dispersion) above which the outflows from these black holes suppress star formation in their hosts by heating and expelling all available cold gas. Supermassive black holes are negligible in mass compared to their hosts but nevertheless seem to play a critical role in the star formation history of galaxies.
Paudel, Sanjaya,Smith, Rory,Duc, Pierre-Alain,Cô,té,, Patrick,Cuillandre, Jean-Charles,Ferrarese, Laura,Blakeslee, John P.,Boselli, Alessandro,Cantiello, Michele,Gwyn, S. D. J.,Guhathakurta American Astronomical Society 2017 The Astrophysical Journal Vol.834 No.1
<P>The Next Generation Virgo Cluster Survey is a deep (with a 2 sigma detection limit mu g = 29 mag arcsec(-2) in the g-band) optical panchromatic survey targeting the Virgo cluster from its core to virial radius, for a total areal coverage of 104 square degrees. As such, the survey is well suited for the study of galaxies' outskirts, haloes, and low surface brightness features that arise from dynamical interactions within the cluster environment. We report the discovery of extremely faint (mu g > 25 mag arcsec(-2)) shells in three Virgo cluster early-type dwarf galaxies: VCC. 1361, VCC. 1447, and VCC. 1668. Among them, VCC. 1447 has an absolute magnitude Mg = -11.71 mag and is the least massive galaxy with a shell system discovered to date. We present a detailed study of these low surface brightness features. We detect between three and four shells in each of our galaxies. Within the uncertainties, we find no evidence of a color difference between the galaxy main body and shell features. The observed arcs of the shells are located up to several effective radii of the galaxies. We further explore the origin of these low surface brightness features with the help of idealized numerical simulations. We find that a near equal mass merger is best able to reproduce the main properties of the shells, including their quite symmetric appearance and their alignment along the major axis of the galaxy. The simulations provide support for a formation scenario in which a recent merger, between two near-equal mass, gas-free dwarf galaxies, forms the observed shell systems.</P>
Evolution of dust temperature of galaxies through cosmic time as seen by <i>Herschel</i><sup>★</sup>
Hwang, H. S.,Elbaz, D.,Magdis, G.,Daddi, E.,Symeonidis, M.,Altieri, B.,Amblard, A.,Andreani, P.,Arumugam, V.,Auld, R.,Aussel, H.,Babbedge, T.,Berta, S.,Blain, A.,Bock, J.,Bongiovanni, A.,Boselli, A.,B Blackwell Publishing Ltd 2010 MONTHLY NOTICES- ROYAL ASTRONOMICAL SOCIETY Vol.409 No.1
<P>ABSTRACT</P><P>We study the dust properties of galaxies in the redshift range 0.1 ≲<I>z</I>≲ 2.8 observed by the <I>Herschel Space Observatory</I> in the field of the Great Observatories Origins Deep Survey-North as part of the PACS Extragalactic Probe (PEP) and <I>Herschel</I> Multi-tiered Extragalactic Survey (HerMES) key programmes. Infrared (IR) luminosity (<I>L</I><SUB>IR</SUB>) and dust temperature (<I>T</I><SUB>dust</SUB>) of galaxies are derived from the spectral energy distribution fit of the far-IR (FIR) flux densities obtained with the PACS and SPIRE instruments onboard <I>Herschel</I>. As a reference sample, we also obtain IR luminosities and dust temperatures of local galaxies at <I>z</I> < 0.1 using <I>AKARI</I> and <I>IRAS</I> data in the field of the Sloan Digital Sky Survey. We compare the <I>L</I><SUB>IR</SUB>–<I>T</I><SUB>dust</SUB> relation between the two samples and find that the median <I>T</I><SUB>dust</SUB> of <I>Herschel</I>-selected galaxies at <I>z</I>≳ 0.5 with <I>L</I><SUB>IR</SUB>≳ 5 × 10<SUP>10</SUP> L<SUB>⊙</SUB> appears to be 2–5 K colder than that of <I>AKARI</I>-selected local galaxies with similar luminosities, and the dispersion in <I>T</I><SUB>dust</SUB> for high-<I>z</I> galaxies increases with <I>L</I><SUB>IR</SUB> due to the existence of cold galaxies that are not seen among local galaxies. We show that this large dispersion of the <I>L</I><SUB>IR</SUB>−<I>T</I><SUB>dust</SUB> relation can bridge the gap between local star-forming galaxies and high-<I>z</I> submillimetre galaxies (SMGs). We also find that three SMGs with very low <I>T</I><SUB>dust</SUB> (≲20 K) covered in this study have close neighbouring sources with similar 24-μm brightness, which could lead to an overestimation of FIR/(sub)millimetre fluxes of the SMGs.</P>