Faculty Opinions recommendation of Inhibition of nuclear import and alteration of nuclear pore complex composition by rhinovirus.

2002 ◽  
Author(s):  
Pamela Silver
Keyword(s):  
Nuclear Pore Complex ◽  
Nuclear Import ◽  
Nuclear Pore ◽  
Complex Composition

scholarly journals SARS-CoV-2 Orf6 hijacks Nup98 to block STAT nuclear import and antagonize interferon signaling

2020 ◽  
Vol 117 (45) ◽  
pp. 28344-28354 ◽  
Author(s):  
Lisa Miorin ◽  
Thomas Kehrer ◽  
Maria Teresa Sanchez-Aparicio ◽  
Ke Zhang ◽  
Phillip Cohen ◽  
...  
Keyword(s):  
Nuclear Pore Complex ◽  
Nuclear Import ◽  
Nuclear Translocation ◽  
Nuclear Pore ◽  
Interferon Signaling ◽  
Antiviral Signaling ◽  
Pathogenic Viruses ◽  
Transcriptional Induction ◽  
Global Health Problem ◽  
Viral Accessory Protein

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is the causative agent of the ongoing coronavirus disease 2019 (COVID-19) pandemic that is a serious global health problem. Evasion of IFN-mediated antiviral signaling is a common defense strategy that pathogenic viruses use to replicate and propagate in their host. In this study, we show that SARS-CoV-2 is able to efficiently block STAT1 and STAT2 nuclear translocation in order to impair transcriptional induction of IFN-stimulated genes (ISGs). Our results demonstrate that the viral accessory protein Orf6 exerts this anti-IFN activity. We found that SARS-CoV-2 Orf6 localizes at the nuclear pore complex (NPC) and directly interacts with Nup98-Rae1 via its C-terminal domain to impair docking of cargo-receptor (karyopherin/importin) complex and disrupt nuclear import. In addition, we show that a methionine-to-arginine substitution at residue 58 impairs Orf6 binding to the Nup98-Rae1 complex and abolishes its IFN antagonistic function. All together our data unravel a mechanism of viral antagonism in which a virus hijacks the Nup98-Rae1 complex to overcome the antiviral action of IFN.

The nuclear pore complex, nuclear transport, and apoptosisThis paper is one of a selection of papers published in this Special Issue, entitled The Nucleus: A Cell Within A Cell.

2006 ◽  
Vol 84 (3-4) ◽  
pp. 279-286 ◽  
Author(s):  
Birthe Fahrenkrog
Keyword(s):  
Nuclear Pore Complex ◽  
Nuclear Import ◽  
Morphological Changes ◽  
Nuclear Transport ◽  
Nuclear Pore ◽  
Simple Fact ◽  
Cell Death Program ◽  
A Cell ◽  
Cellular Compartments ◽  
Selection Of

The nuclear pore complex (NPC) is the sole gateway between the nucleus and the cytoplasm of interphase eukaryotic cells, and it mediates all trafficking between these 2 cellular compartments. As such, the NPC and nuclear transport play central roles in translocating death signals from the cell membrane to the nucleus where they initiate biochemical and morphological changes occurring during apoptosis. Recent findings suggest that the correlation between the NPC, nuclear transport, and apoptosis goes beyond the simple fact that NPCs mediate nuclear transport of key players involved in the cell death program. In this context, the accessibility of key regulators of apoptosis appears to be highly modulated by nuclear transport (e.g., impaired nuclear import might be an apoptotic trigger). In this review, recent findings concerning the unexpected tight link between NPCs, nuclear transport, and apoptosis will be presented and critically discussed.

scholarly journals Simple kinetic relationships and nonspecific competition govern nuclear import rates in vivo

2006 ◽  
Vol 175 (4) ◽  
pp. 579-593 ◽  
Author(s):  
Benjamin L. Timney ◽  
Jaclyn Tetenbaum-Novatt ◽  
Diana S. Agate ◽  
Rosemary Williams ◽  
Wenzhu Zhang ◽  
...  
Keyword(s):  
Nuclear Localization ◽  
Nuclear Pore Complex ◽  
Nuclear Import ◽  
Yeast Cells ◽  
Limiting Factor ◽  
Nuclear Pore ◽  
Nuclear Localization Signals ◽  
The Poor ◽  
Cytoplasmic Proteins

Many cargoes destined for nuclear import carry nuclear localization signals that are recognized by karyopherins (Kaps). We present methods to quantitate import rates and measure Kap and cargo concentrations in single yeast cells in vivo, providing new insights into import kinetics. By systematically manipulating the amounts, types, and affinities of Kaps and cargos, we show that import rates in vivo are simply governed by the concentrations of Kaps and their cargo and the affinity between them. These rates fit to a straightforward pump–leak model for the import process. Unexpectedly, we deduced that the main limiting factor for import is the poor ability of Kaps and cargos to find each other in the cytoplasm in a background of overwhelming nonspecific competition, rather than other more obvious candidates such as the nuclear pore complex and Ran. It is likely that most of every import round is taken up by Kaps and nuclear localization signals sampling other cytoplasmic proteins as they locate each other in the cytoplasm.

scholarly journals Monoclonal Antibodies to NTF2 Inhibit Nuclear Protein Import by Preventing Nuclear Translocation of the GTPase Ran

2000 ◽  
Vol 11 (2) ◽  
pp. 703-719 ◽  
Author(s):  
Susanne M. Steggerda ◽  
Ben E. Black ◽  
Bryce M. Paschal
Keyword(s):  
Nuclear Pore Complex ◽  
Nuclear Import ◽  
Protein Import ◽  
Nuclear Translocation ◽  
Living Cells ◽  
Nuclear Accumulation ◽  
Nuclear Pore ◽  
Permeabilized Cells ◽  
Dependent Protein

Nuclear transport factor 2 (NTF2) is a soluble transport protein originally identified by its ability to stimulate nuclear localization signal (NLS)-dependent protein import in digitonin-permeabilized cells. NTF2 has been shown to bind nuclear pore complex proteins and the GDP form of Ran in vitro. Recently, it has been reported that NTF2 can stimulate the accumulation of Ran in digitonin-permeabilized cells. Evidence that NTF2 directly mediates Ran import or that NTF2 is required to maintain the nuclear concentration of Ran in living cells has not been obtained. Here we show that cytoplasmic injection of anti-NTF2 mAbs resulted in a dramatic relocalization of Ran to the cytoplasm. This provides the first evidence that NTF2 regulates the distribution of Ran in vivo. Moreover, anti-NTF2 mAbs inhibited nuclear import of both Ran and NLS-containing protein in vitro, suggesting that NTF2 stimulates NLS-dependent protein import by driving the nuclear accumulation of Ran. We also show that biotinylated NTF2-streptavidin microinjected into the cytoplasm accumulated at the nuclear envelope, indicating that NTF2 can target a binding partner to the nuclear pore complex. Taken together, our data show that NTF2 is an essential regulator of the Ran distribution in living cells and that NTF2-mediated Ran nuclear import is required for NLS-dependent protein import.

scholarly journals GTP hydrolysis by Ran occurs at the nuclear pore complex in an early step of protein import.

1995 ◽  
Vol 131 (3) ◽  
pp. 571-581 ◽  
Author(s):  
F Melchior ◽  
T Guan ◽  
N Yokoyama ◽  
T Nishimoto ◽  
L Gerace
Keyword(s):  
Nuclear Pore Complex ◽  
Nuclear Import ◽  
Protein Import ◽  
Small Gtpase ◽  
Nuclear Pore ◽  
Binding Studies ◽  
Early Step ◽  
Permeabilized Cells ◽  
Complex Protein ◽  
Ran Gtp

Mediated import of proteins into the nucleus involves multiple cytosolic factors, including the small GTPase Ran. Whether Ran functions by interacting with other cytosolic proteins or components of the nuclear pore complex has been unclear. Furthermore, the precise transport step where Ran acts has not been determined. To address these questions, we have analyzed the binding interactions of Ran using permeabilized cells and isolated nuclear envelopes. By light and electron microscope immunolocalization, we have found that Ran accumulates specifically at the cytoplasmic surface of the nuclear pore complex when nuclear import in permeabilized cells is inhibited by nonhydrolyzable analogs of GTP. Ran associates with a peripheral pore complex region that is similar to the area where transport ligands accumulate by depletion of ATP, which arrests an early step of transport. Binding studies with isolated nuclear envelopes in the absence of added cytosol indicate that Ran-GTP directly interacts with a pore complex protein. Using blot overlay techniques, we detected a single prominent polypeptide of isolated nuclear envelopes that binds Ran-GTP. This corresponds to the 358-kD protein RanBP2, a Ran binding pore complex protein recently identified by two-hybrid screening. Thus, RanBP2 is likely to constitute the Ran-GTP-binding site detected at the cytoplasmic periphery of the pore complex. These data support a model in which initial ligand binding to the nuclear pore complex occurs at or near RanBP2, and that hydrolysis of GTP by Ran at this site serves to define commitment to the nuclear import pathway.

scholarly journals The cytoplasmic filaments of the nuclear pore complex are dispensable for selective nuclear protein import

2002 ◽  
Vol 158 (1) ◽  
pp. 63-77 ◽  
Author(s):  
Tobias C. Walther ◽  
Helen S. Pickersgill ◽  
Volker C. Cordes ◽  
Martin W. Goldberg ◽  
Terry D. Allen ◽  
...  
Keyword(s):  
Nuclear Pore Complex ◽  
Nuclear Import ◽  
Protein Import ◽  
Nuclear Localization Sequence ◽  
Nuclear Pore ◽  
Slight Reduction ◽  
Cytoplasmic Filaments ◽  
Localization Sequence ◽  
Importin Α

The nuclear pore complex (NPC) mediates bidirectional macromolecular traffic between the nucleus and cytoplasm in eukaryotic cells. Eight filaments project from the NPC into the cytoplasm and are proposed to function in nuclear import. We investigated the localization and function of two nucleoporins on the cytoplasmic face of the NPC, CAN/Nup214 and RanBP2/Nup358. Consistent with previous data, RanBP2 was localized at the cytoplasmic filaments. In contrast, CAN was localized near the cytoplasmic coaxial ring. Unexpectedly, extensive blocking of RanBP2 with gold-conjugated antibodies failed to inhibit nuclear import. Therefore, RanBP2-deficient NPCs were generated by in vitro nuclear assembly in RanBP2-depleted Xenopus egg extracts. NPCs were formed that lacked cytoplasmic filaments, but that retained CAN. These nuclei efficiently imported nuclear localization sequence (NLS) or M9 substrates. NPCs lacking CAN retained RanBP2 and cytoplasmic filaments, and showed a minor NLS import defect. NPCs deficient in both CAN and RanBP2 displayed no cytoplasmic filaments and had a strikingly immature cytoplasmic appearance. However, they showed only a slight reduction in NLS-mediated import, no change in M9-mediated import, and were normal in growth and DNA replication. We conclude that RanBP2 is the major nucleoporin component of the cytoplasmic filaments of the NPC, and that these filaments do not have an essential role in importin α/β– or transportin-dependent import.

Carrier-Independent Nuclear Import of the Transcription Factor PU.1.

Blood ◽  
2004 ◽  
Vol 104 (11) ◽  
pp. 3561-3561
Author(s):  
Nabeel R. Yaseen ◽  
Akiko Takeda ◽  
Reza Nazari ◽  
Helen Shio ◽  
Gunter Blobel ◽  
...  
Keyword(s):  
Transcription Factor ◽  
Nuclear Localization ◽  
Nuclear Pore Complex ◽  
Nuclear Import ◽  
Nuclear Pore ◽  
Permeabilized Cells ◽  
Ultrastructural Studies ◽  
Ets Family ◽  
Ets Domain ◽  
Necessary And Sufficient

Abstract PU.1 is a transcription factor of the Ets family with important functions in hematopoietic cell differentiation. Using GFP-PU.1 fusions, we show that the Ets DNA-binding domain of PU.1 is necessary and sufficient for its nuclear localization. Fluorescence and ultrastructural nuclear import assays showed that PU.1 nuclear import requires energy but not soluble carriers. PU.1 interacted with the FG repeats of nucleoporins Nup62 and Nup153. The binding of PU.1 to Nup153, but not to Nup62, dramatically increased in the presence of RanGMPPNP, indicating the formation of a PU.1/RanGTP/Nup153 complex. The Ets domain accounted for the bulk of the interaction of PU.1 with Nup153 and RanGMPPNP. Since Nup62 is located close to the midplane of the nuclear pore complex (NPC) while Nup153 is at its nuclear side, these findings suggest a model whereby RanGTP propels PU.1 towards the nuclear side of the NPC by increasing its affinity for Nup153. This notion was confirmed by ultrastructural studies using gold-labeled PU.1 in permeabilized cells.

scholarly journals Inhibition of Nuclear Import and Alteration of Nuclear Pore Complex Composition by Rhinovirus

2002 ◽  
Vol 76 (17) ◽  
pp. 8787-8796 ◽  
Author(s):  
Kurt E. Gustin ◽  
Peter Sarnow
Keyword(s):  
Nuclear Pore Complex ◽  
Nuclear Import ◽  
Nuclear Proteins ◽  
Nuclear Pore ◽  
Nucleocytoplasmic Trafficking ◽  
The Status ◽  
Infected Cells ◽  
Novel Strategy ◽  
In Cells

ABSTRACT Nucleocytoplasmic trafficking pathways and the status of nuclear pore complex (NPC) components were examined in cells infected with rhinovirus type 14. A variety of shuttling and nonshuttling nuclear proteins, using multiple nuclear import pathways, accumulated in the cytoplasm of cells infected with rhinovirus. An in vitro nuclear import assay with semipermeabilized infected cells confirmed that nuclear import was inhibited and that docking of nuclear import receptor-cargo complexes at the cytoplasmic face of the NPC was prevented in rhinovirus-infected cells. The relocation of cellular proteins and inhibition of nuclear import correlated with the degradation of two NPC components, Nup153 and p62. The degradation of Nup153 and p62 was not due to induction of apoptosis, because p62 was not proteolyzed in apoptotic HeLa cells, and Nup153 was cleaved to produce a 130-kDa cleavage product that was not observed in cells infected with poliovirus or rhinovirus. The finding that both poliovirus and rhinovirus cause inhibition of nuclear import and degradation of NPC components suggests that this may be a common feature of the replicative cycle of picornaviruses. Inhibition of nuclear import is predicted to result in the cytoplasmic accumulation of a large number of nuclear proteins that could have functions in viral translation, RNA synthesis, packaging, or assembly. Additionally, inhibition of nuclear import also presents a novel strategy whereby cytoplasmic RNA viruses can evade host immune defenses by preventing signal transduction into the nucleus.

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