scholarly journals CRM1 promotes capsid disassembly and nuclear envelope translocation of adenovirus independently of its export function

2021 ◽  
Author(s):  
Floriane Lagadec ◽  
Irene Carlon-Andres ◽  
Jessica Ragues ◽  
Sarah Port ◽  
Harald Wodrich ◽  
...  
Keyword(s):  
Nuclear Export ◽  
Nuclear Pore ◽  
Nuclear Pore Complexes ◽  
Microtubule Organizing Center ◽  
Leptomycin B ◽  
Pore Complexes ◽  
Nuclear Export Receptor ◽  
Mitotic Cells ◽  
Capsid Disassembly

After receptor-mediated endocytosis and endosomal escape, adenoviral capsids can travel via microtubule organizing centers to the nuclear envelope. Upon capsid disassembly, viral genome import into nuclei of interphase cells then occurs through nuclear pore complexes, involving the nucleoporins Nup214 and Nup358. Import also requires the activity of the classic nuclear export receptor CRM1, as it is blocked by the selective inhibitor leptomycin B. We have now used artificially enucleated as well as mitotic cells to analyze the role of an intact nucleus in different steps of the viral life cycle. In enucleated U2OS cells, viral capsids traveled to the microtubule organizing center, whereas their removal from this complex was blocked, suggesting that this step required nuclear factors. In mitotic cells, on the other hand, CRM1 promoted capsid disassembly and genome release, suggesting a role of this protein that does not require intact nuclear envelopes or nuclear pore complexes and is distinct from its function as a nuclear export receptor. Similar to enucleation, inhibition of CRM1 by leptomycin B also leads to an arrest of adenoviral capsids at the microtubule organizing center. In a small-scale screen using leptomycin B-resistant versions of CRM1, we identified a mutant, CRM1 W142A P143A, that is compromised with respect to adenoviral capsid disassembly, both in interphase and in mitotic cells. Strikingly, this mutant is capable of exporting cargo proteins out of the nucleus of living cells or digitonin-permeabilized cells, pointing to a role of the mutated region that is not directly linked to nuclear export. IMPORTANCE A role of nucleoporins and of soluble transport factors in adenoviral genome import into the nucleus of infected cells in interphase has previously been established. The nuclear export receptor CRM1 promotes genome import, but its precise function is not known. Using enucleated and mitotic cells, we showed that CRM1 does not simply function by exporting a crucial factor out of the nucleus that would then trigger capsid disassembly and genome import. Instead, CRM1 has an export-independent role, a notion that is also supported by a mutant, CRM1 W142A P143A, which is export-competent but deficient in viral capsid disassembly, both in interphase and in mitotic cells.

scholarly journals Distinct Basket Nucleoporins roles in Nuclear Pore Function and Gene Expression: Tpr is an integral component of the TREX-2 mRNA export pathway

2019 ◽  
Author(s):  
Vasilisa Aksenova ◽  
Hang Noh Lee ◽  
Alexandra Smith ◽  
Shane Chen ◽  
Prasanna Bhat ◽  
...  
Keyword(s):  
Gene Expression ◽  
Nuclear Export ◽  
Protein Modification ◽  
Mrna Export ◽  
Nuclear Pore ◽  
Nuclear Pore Complexes ◽  
Nucleocytoplasmic Trafficking ◽  
Pore Complexes ◽  
Slow Turnover

AbstractNuclear pore complexes (NPCs) are important for many processes beyond nucleocytoplasmic trafficking, including protein modification, chromatin remodeling, transcription, mRNA processing and mRNA export. The multi-faceted nature of NPCs and the slow turnover of their components has made it difficult to understand the role of basket nucleoporins (Nup153, Nup50 and Tpr) in these diverse processes. To address this question, we used anAuxin-InducedDegron (AID) system to distinguish roles of basket nucleoporins: Loss of individual nucleoporins caused distinct alteration in patterns of nucleocytoplasmic trafficking and gene expression. Importantly, Tpr elimination caused rapid and pronounced changes in transcriptomic profiles within two hours of auxin addition. These changes were dissimilar to shifts observed after loss of Nup153 or Nup50, but closely related to changes after depletion of mRNA export receptor NXF1 or the GANP subunit of the TRanscription-EXport-2 (TREX-2) mRNA export complex. Moreover, GANP association to NPCs was specifically disrupted upon TPR depletion. Together, our findings demonstrate a unique and pivotal role of Tpr in regulating gene expression through GANP- and/or NXF1-dependent mRNA nuclear export.

scholarly journals p53 SUMOylation promotes its nuclear export by facilitating its release from the nuclear export receptor CRM1

2013 ◽  
Vol 24 (17) ◽  
pp. 2739-2752 ◽  
Author(s):  
Aleixo Santiago ◽  
Dawei Li ◽  
Lisa Y. Zhao ◽  
Adam Godsey ◽  
Daiqing Liao
Keyword(s):  
Nuclear Export ◽  
Nuclear Export Signal ◽  
Underlying Mechanism ◽  
Binding Pocket ◽  
Nuclear Pore ◽  
Nuclear Pore Complexes ◽  
Subunit Dissociation ◽  
Binding Groove ◽  
Pore Complexes ◽  
Nuclear Export Receptor

Chromosomal region maintenance 1 (CRM1) mediates p53 nuclear export. Although p53 SUMOylation promotes its nuclear export, the underlying mechanism is unclear. Here we show that tethering of a small, ubiquitin-like modifier (SUMO) moiety to p53 markedly increases its cytoplasmic localization. SUMO attachment to p53 does not affect its oligomerization, suggesting that subunit dissociation required for exposing p53’s nuclear export signal (NES) is unnecessary for p53 nuclear export. Surprisingly, SUMO-mediated p53 nuclear export depends on the SUMO-interacting motif (SIM)-binding pocket of SUMO-1. The CRM1 C-terminal domain lacking the NES-binding groove interacts with tetrameric p53, and the proper folding of the p53 core domain, rather than the presence of the N- or C-terminal tails, appears to be important for p53–CRM1 interaction. The CRM1 Huntington, EF3, a subunit of PP2A, and TOR1 9 (HEAT9) loop, which regulates GTP-binding nuclear protein Ran binding and cargo release, contains a prototypical SIM. Remarkably, disruption of this SIM in conjunction with a mutated SIM-binding groove of SUMO-1 markedly enhances the binding of CRM1 to p53-SUMO-1 and their accumulation in the nuclear pore complexes (NPCs), as well as their persistent association in the cytoplasm. We propose that SUMOylation of a CRM1 cargo such as p53 at the NPCs unlocks the HEAT9 loop of CRM1 to facilitate the disassembly of the transporting complex and cargo release to the cytoplasm.

scholarly journals The nuclear pore complex: mediator of translocation between nucleus and cytoplasm

2000 ◽  
Vol 113 (10) ◽  
pp. 1651-1659 ◽  
Author(s):  
T.D. Allen ◽  
J.M. Cronshaw ◽  
S. Bagley ◽  
E. Kiseleva ◽  
M.W. Goldberg
Keyword(s):  
Nuclear Export ◽  
Mammalian Cells ◽  
Complex Structure ◽  
Nuclear Pore ◽  
Nuclear Pore Complexes ◽  
Complete Breakdown ◽  
Import And Export ◽  
Complex Structural ◽  
Pore Complexes ◽  
Giant Nuclei

The enclosure of nuclear contents in eukaryotes means that cells require sites in the boundary that mediate exchange of material between nucleus and cytoplasm. These sites, termed nuclear pore complexes (NPCs), number 100–200 in yeast, a few thousand in mammalian cells and approximately 50 million in the giant nuclei of amphibian oocytes. NPCs are large (125 MDa) macromolecular complexes that comprise 50–100 different proteins in vertebrates. In spite of their size and complex structure, NPCs undergo complete breakdown and reformation at cell division. Transport through NPCs can be rapid (estimated at several hundred molecules/pore/second) and accommodates both passive diffusion of relatively small molecules, and active transport of complexes up to several megadaltons in molecular mass. Each pore can facilitate both import and export. The two processes apparently involve multiple pathways for different cargoes, and their transport signals, transport receptors and adapters, and the molecules (and their regulators) that underpin the transport mechanisms. Over the past few years there has been an increasing interest in the pore complex: structural studies have been followed by elucidation of the biochemical aspects of nuclear import, and subsequent investigations into nuclear export. The current challenge is to understand the interactions between the structural elements of the pore complex and the mechanisms that drive the physical processes of translocation through it.

scholarly journals RanBP2/Nup358 Provides a Major Binding Site for NXF1-p15 Dimers at the Nuclear Pore Complex and Functions in Nuclear mRNA Export

2004 ◽  
Vol 24 (3) ◽  
pp. 1155-1167 ◽  
Author(s):  
Daniel Forler ◽  
Gwénaël Rabut ◽  
Francesca D. Ciccarelli ◽  
Andrea Herold ◽  
Thomas Köcher ◽  
...  
Keyword(s):  
Binding Site ◽  
Nuclear Export ◽  
Mrna Export ◽  
Stable Complex ◽  
Nuclear Pore ◽  
Nuclear Pore Complexes ◽  
Cytoplasmic Filaments ◽  
Nuclear Levels ◽  
Pore Complexes

ABSTRACT Metazoan NXF1-p15 heterodimers promote the nuclear export of bulk mRNA across nuclear pore complexes (NPCs). In vitro, NXF1-p15 forms a stable complex with the nucleoporin RanBP2/Nup358, a component of the cytoplasmic filaments of the NPC, suggesting a role for this nucleoporin in mRNA export. We show that depletion of RanBP2 from Drosophila cells inhibits proliferation and mRNA export. Concomitantly, the localization of NXF1 at the NPC is strongly reduced and a significant fraction of this normally nuclear protein is detected in the cytoplasm. Under the same conditions, the steady-state subcellular localization of other nuclear or cytoplasmic proteins and CRM1-mediated protein export are not detectably affected, indicating that the release of NXF1 into the cytoplasm and the inhibition of mRNA export are not due to a general defect in NPC function. The specific role of RanBP2 in the recruitment of NXF1 to the NPC is highlighted by the observation that depletion of CAN/Nup214 also inhibits cell proliferation and mRNA export but does not affect NXF1 localization. Our results indicate that RanBP2 provides a major binding site for NXF1 at the cytoplasmic filaments of the NPC, thereby restricting its diffusion in the cytoplasm after NPC translocation. In RanBP2-depleted cells, NXF1 diffuses freely through the cytoplasm. Consequently, the nuclear levels of the protein decrease and export of bulk mRNA is impaired.

scholarly journals Steady-State Nuclear Localization of Exportin-t Involves RanGTP Binding and Two Distinct Nuclear Pore Complex Interaction Domains

2002 ◽  
Vol 22 (16) ◽  
pp. 5708-5720 ◽  
Author(s):  
Scott Kuersten ◽  
Gert-Jan Arts ◽  
Tobias C. Walther ◽  
Ludwig Englmeier ◽  
Iain W. Mattaj
Keyword(s):  
Steady State ◽  
Nuclear Export ◽  
Nuclear Pore ◽  
Nuclear Pore Complexes ◽  
Dependent Manner ◽  
C Terminus ◽  
Transport Cycle ◽  
Interaction Domains ◽  
Pore Complexes

ABSTRACT Vertebrate tRNA export receptor exportin-t (Xpo-t) binds to RanGTP and mature tRNAs cooperatively to form a nuclear export complex. Xpo-t shuttles bidirectionally through nuclear pore complexes (NPCs) but is mainly nuclear at steady state. The steady-state distribution of Xpo-t is shown to depend on its interaction with RanGTP. Two distinct Xpo-t NPC interaction domains that bind differentially to peripherally localized nucleoporins in vitro are identified. The N terminus binds to both Nup153 and RanBP2/Nup358 in a RanGTP-dependent manner, while the C terminus binds to CAN/Nup214 independently of Ran. We propose that these interactions increase the concentration of tRNA export complexes and of empty Xpo-t in the vicinity of NPCs and thus increase the efficiency of the Xpo-t transport cycle.

scholarly journals Altered RNA processing and export lead to retention of mRNAs near transcription sites and nuclear pore complexes or within the nucleolus

2016 ◽  
Vol 27 (17) ◽  
pp. 2742-2756 ◽  
Author(s):  
Biplab Paul ◽  
Ben Montpetit
Keyword(s):  
Single Molecule ◽  
Rna Processing ◽  
Nuclear Export ◽  
Essential Gene ◽  
Nucleocytoplasmic Transport ◽  
Nuclear Pore ◽  
Nuclear Pore Complexes ◽  
Eukaryotic Gene ◽  
Transcription Sites ◽  
Pore Complexes

Many protein factors are required for mRNA biogenesis and nuclear export, which are central to the eukaryotic gene expression program. It is unclear, however, whether all factors have been identified. Here we report on a screen of >1000 essential gene mutants in Saccharomyces cerevisiae for defects in mRNA processing and export, identifying 26 mutants with defects in this process. Single-molecule FISH data showed that the majority of these mutants accumulated mRNA within specific regions of the nucleus, which included 1) mRNAs within the nucleolus when nucleocytoplasmic transport, rRNA biogenesis, or RNA processing and surveillance was disrupted, 2) the buildup of mRNAs near transcription sites in 3′-end processing and chromosome segregation mutants, and 3) transcripts being enriched near nuclear pore complexes when components of the mRNA export machinery were mutated. These data show that alterations to various nuclear processes lead to the retention of mRNAs at discrete locations within the nucleus.

scholarly journals Nuclear Pore Complex Acetylation Regulates mRNA Export and Cell Cycle Commitment in Budding Yeast

2021 ◽  
Author(s):  
Mercè Gomar-Alba ◽  
Vasilisa Pozharskaia ◽  
Celia Schaal ◽  
Arun Kumar ◽  
Basile Jacquel ◽  
...  
Keyword(s):  
Gene Expression ◽  
Nuclear Export ◽  
Mrna Export ◽  
Cell Types ◽  
Nuclear Pore ◽  
Specific Cell ◽  
Nuclear Pore Complexes ◽  
Daughter Cells ◽  
Associated Proteins ◽  
Pore Complexes

AbstractNuclear pore complexes (NPCs) mediate communication between the nucleus and the cytoplasm and regulate gene expression by interacting with transcription and mRNA export factors. Lysine acetyl-transferases (KATs) promote transcription through acetylation of chromatin-associated proteins. We find that Esa1, the KAT subunit of the yeast NuA4 complex, also acetylates the nuclear pore basket component Nup60 to promote mRNA export. Acetylation of Nup60 recruits mRNA export factors to the nuclear basket, including the scaffolding subunit of the Transcription and Export 2 (TREX-2) complex, Sac3. Esa1-dependent nuclear export of mRNAs promotes entry into S phase, and is inhibited by the Hos3 deacetylase in G1 daughter cells to restrain their premature commitment to a new cell division cycle. This mechanism also inhibits expression of the nutrient-regulated GAL1 gene specifically in daughter cells. These results reveal how acetylation contributes to the functional plasticity of NPCs in specific cell types, and demonstrate how the evolutionarily conserved NuA4 complex regulates gene expression dually at the level of transcription and mRNA export, by modifying the nucleoplasmic entrance to nuclear pores.

scholarly journals Nucleoporin TPR is an integral component of the TREX-2 mRNA export pathway

2020 ◽  
Vol 11 (1) ◽  
Author(s):  
Vasilisa Aksenova ◽  
Alexandra Smith ◽  
Hangnoh Lee ◽  
Prasanna Bhat ◽  
Caroline Esnault ◽  
...  
Keyword(s):  
Gene Expression ◽  
Mrna Export ◽  
Mrna Turnover ◽  
Nuclear Pore ◽  
Nuclear Pore Complexes ◽  
Nucleocytoplasmic Trafficking ◽  
Cellular Functions ◽  
Pore Complexes ◽  
Slow Turnover

Abstract Nuclear pore complexes (NPCs) are important for cellular functions beyond nucleocytoplasmic trafficking, including genome organization and gene expression. This multi-faceted nature and the slow turnover of NPC components complicates investigations of how individual nucleoporins act in these diverse processes. To address this question, we apply an Auxin-Induced Degron (AID) system to distinguish roles of basket nucleoporins NUP153, NUP50 and TPR. Acute depletion of TPR causes rapid and pronounced changes in transcriptomic profiles. These changes are dissimilar to shifts observed after loss of NUP153 or NUP50, but closely related to changes caused by depletion of mRNA export receptor NXF1 or the GANP subunit of the TRanscription-EXport-2 (TREX-2) mRNA export complex. Moreover, TPR depletion disrupts association of TREX-2 subunits (GANP, PCID2, ENY2) to NPCs and results in abnormal RNA transcription and export. Our findings demonstrate a unique and pivotal role of TPR in gene expression through TREX-2- and/or NXF1-dependent mRNA turnover.

scholarly journals The Role of Nucleoporin Elys in Nuclear Pore Complex Assembly and Regulation of Genome Architecture

2020 ◽  
Vol 21 (24) ◽  
pp. 9475
Author(s):  
Yuri Y. Shevelyov
Keyword(s):  
Nuclear Envelope ◽  
Nuclear Pore Complex ◽  
Nuclear Lamina ◽  
Nuclear Pore ◽  
Genome Architecture ◽  
Nuclear Pore Complexes ◽  
Current State ◽  
Long Time ◽  
Pore Complexes

For a long time, the nuclear lamina was thought to be the sole scaffold for the attachment of chromosomes to the nuclear envelope (NE) in metazoans. However, accumulating evidence indicates that nuclear pore complexes (NPCs) comprised of nucleoporins (Nups) participate in this process as well. One of the Nups, Elys, initiates NPC reassembly at the end of mitosis. Elys directly binds the decondensing chromatin and interacts with the Nup107–160 subcomplex of NPCs, thus serving as a seeding point for the subsequent recruitment of other NPC subcomplexes and connecting chromatin with the re-forming NE. Recent studies also uncovered the important functions of Elys during interphase where it interacts with chromatin and affects its compactness. Therefore, Elys seems to be one of the key Nups regulating chromatin organization. This review summarizes the current state of our knowledge about the participation of Elys in the post-mitotic NPC reassembly as well as the role that Elys and other Nups play in the maintenance of genome architecture.

Sign in / Sign up

Export Citation Format

Share Document