NXF-2, REF-1, and REF-2 Affect the Choice of Nuclear Export Pathway for tra-2 mRNA in C. elegans

Soluble factors are required to mediate nuclear export of protein and RNA through the nuclear pore complex (NPC). These soluble factors include receptors that bind directly to the transport substrate and regulators that determine the assembly state of receptor–substrate complexes. We recently reported the identification of NXT1, an NTF2-related export factor that stimulates nuclear protein export in permeabilized cells and undergoes nucleocytoplasmic shuttling in vivo (Black, B.E., L. Lévesque, J.M. Holaska, T.C. Wood, and B.M. Paschal. 1999. Mol. Cell. Biol. 19:8616–8624). Here, we describe the molecular characterization of NXT1 in the context of the Crm1-dependent export pathway. We find that NXT1 binds directly to Crm1, and that the interaction is sensitive to the presence of Ran-GTP. Moreover, mutations in NXT1 that reduce binding to Crm1 inhibit the activity of NXT1 in nuclear export assays. We show that recombinant Crm1 and Ran are sufficient to reconstitute nuclear translocation of a Rev reporter protein from the nucleolus to an antibody accessible site on the cytoplasmic side of the NPC. Further progress on the export pathway, including the terminal step of Crm1 and Rev reporter protein release, requires NXT1. We propose that NXT1 engages with the export complex in the nucleoplasm, and that it facilitates delivery of the export complex to a site on the cytoplasmic side of NPC where the receptor and substrate are released into the cytoplasm.

Download Full-text

Phosphorylation by the β-Catenin/MAPK Complex Promotes 14-3-3-Mediated Nuclear Export of TCF/POP-1 in Signal-Responsive Cells in C. elegans

Cell ◽

10.1016/s0092-8674(04)00203-x ◽

2004 ◽

Vol 117 (1) ◽

pp. 95-106 ◽

Cited By ~ 100

Author(s):

Miao-Chia Lo ◽

Frédérique Gay ◽

Raanan Odom ◽

Yang Shi ◽

Rueyling Lin

Keyword(s):

Nuclear Export ◽

C Elegans

Download Full-text

The BRO proteins of Bombyx mori nucleopolyhedrovirus are nucleocytoplasmic shuttling proteins that utilize the CRM1-mediated nuclear export pathway

Virology ◽

10.1016/j.virol.2006.01.008 ◽

2006 ◽

Vol 350 (1) ◽

pp. 184-191 ◽

Cited By ~ 25

Author(s):

WonKyung Kang ◽

Masaaki Kurihara ◽

Shogo Matsumoto

Keyword(s):

Bombyx Mori ◽

Nuclear Export ◽

Nucleocytoplasmic Shuttling ◽

Bombyx Mori Nucleopolyhedrovirus ◽

Export Pathway

Download Full-text

Molecular profiling of anastatic cancer cells: potential role of the nuclear export pathway

Cellular Oncology ◽

10.1007/s13402-019-00451-1 ◽

2019 ◽

Vol 42 (5) ◽

pp. 645-661 ◽

Cited By ~ 5

Author(s):

Mahendra Seervi ◽

S. Sumi ◽

Aneesh Chandrasekharan ◽

Abhay K. Sharma ◽

T. R. SanthoshKumar

Keyword(s):

Cancer Cells ◽

Nuclear Export ◽

Potential Role ◽

Molecular Profiling ◽

Export Pathway

Download Full-text

Inhibition of Cd83 Cell Surface Expression during Dendritic Cell Maturation by Interference with Nuclear Export of Cd83 mRNA

Journal of Experimental Medicine ◽

10.1084/jem.191.9.1581 ◽

2000 ◽

Vol 191 (9) ◽

pp. 1581-1590 ◽

Cited By ~ 101

Author(s):

Monika Kruse ◽

Olaf Rosorius ◽

Friedrich Krätzer ◽

Dorian Bevec ◽

Christine Kuhnt ◽

...

Keyword(s):

Nuclear Export ◽

Molecular Level ◽

Lymphocyte Activation ◽

Surface Expression ◽

Dendritic Cell Maturation ◽

Initiation Factor ◽

Cell Surface Expression ◽

Export Pathway ◽

Dc Maturation

Dendritic cells (DCs), nature's adjuvant, must mature to sensitize T cells. However, although the maturation process is essential, it is not yet fully understood at the molecular level. In this study, we investigated the course of expression of the unique hypusine-containing protein eukaryotic initiation factor 5A (eIF-5A), which is part of a particular RNA nuclear export pathway, during in vitro generation of human DCs. We show that eIF-5A expression is significantly upregulated during DC maturation. Furthermore, an inhibitor of the hypusine modification, GC7 (N1-guanyl-1,7-diaminoheptane), prevents CD83 surface expression by apparently interfering with nucleocytoplasmic translocation of the CD83 mRNA and, importantly, significantly inhibits DC-mediated T lymphocyte activation. The data presented suggest that CD83 mRNA is transported from the nucleus to the cytoplasm via a specific nuclear export pathway and that hypusine formation appears to be essential for the maturation of functional DCs. Therefore, pharmacological interference with hypusine formation may provide a new possibility to modulate DC function.

Download Full-text

Nucleocytoplasmic Shuttling of Porcine Parvovirus NS1 Protein Mediated by the CRM1 Nuclear Export Pathway and the Importin α/β Nuclear Import Pathway

Journal of Virology ◽

10.1128/jvi.01481-21 ◽

2021 ◽

Author(s):

Liyan Cao ◽

Fang Fu ◽

Jianfei Chen ◽

Hongyan Shi ◽

Xin Zhang ◽

...

Keyword(s):

Amino Acids ◽

Nuclear Import ◽

Nuclear Export ◽

Nonstructural Protein ◽

Nuclear Pore ◽

Porcine Parvovirus ◽

Ns1 Protein ◽

Nucleocytoplasmic Shuttling ◽

Export Pathway ◽

Importin Α

Porcine parvovirus (PPV) NS1, the major nonstructural protein of this virus, plays an important role in PPV replication. We show, for the first time, that NS1 dynamically shuttles between the nucleus and cytoplasm, although its subcellular localization is predominantly nuclear. NS1 contains two nuclear export signals (NESs) at amino acids 283–291 (designated NES2) and 602–608 (designated NES1). NES1 and NES2 are both functional and transferable NESs, and their nuclear export activity is blocked by leptomycin B (LMB), suggesting that the export of NS1 from the nucleus is dependent upon the chromosome region maintenance 1 (CRM1) pathway. Deletion and site-directed mutational analyses showed that NS1 contains a bipartite nuclear localization signal (NLS) at amino acids 256–274. Coimmunoprecipitation assays showed that NS1 interacts with importins α5 and α7 through its NLS. The overexpression of CRM1, importins α5 and α7 significantly promoted PPV replication, whereas the inhibition of CRM1 and importin α/β-mediated transport by specific inhibitors (LMB, importazole and ivermectin) clearly blocked PPV replication. The mutant viruses of delete NESs or NLS motif of the NS1 by using reverse genetics could not be rescued, suggesting that NESs and NLS are essential for PPV replication. Collectively, these findings suggest that NS1 shuttles between the nucleus and cytoplasm, mediated by its functional NESs and NLS, via the CRM1-dependent nuclear export pathway and the importin α/β-mediated nuclear import pathway, and PPV proliferation was inhibited if blocking NS1 nuclear import or export. Importance PPV replicates in the nucleus, and the nuclear envelope is a barrier to its entry into and egress from the nucleus. PPV NS1 is a nucleus-targeting protein that is important for viral DNA replication. Because the NS1 molecule is large (> 50 kDa), it cannot pass through the nuclear pore complex by diffusion alone, and requires specific transport receptors to permit its nucleocytoplasmic shuttling. In this study, the two functional NESs in the NS1 protein were identified, and its dependence on the CRM1 pathway for nuclear export demonstrated. The nuclear import of NS1 utilizes importins α5 and α7 in the importin α/β nuclear import pathway.

Download Full-text

Feline Immunodeficiency Virus Gag Is a Nuclear Shuttling Protein

Journal of Virology ◽

10.1128/jvi.00692-12 ◽

2012 ◽

Vol 86 (16) ◽

pp. 8402-8411 ◽

Cited By ~ 17

Author(s):

Iris Kemler ◽

Dyana Saenz ◽

Eric Poeschla

Keyword(s):

Feline Immunodeficiency Virus ◽

Nuclear Export ◽

Leptomycin B ◽

Genomic Rnas ◽

Intracellular Location ◽

Export Pathway ◽

Immunodeficiency Virus ◽

Nuclear Shuttling ◽

Rna Interaction ◽

Hiv 1

Lentiviral genomic RNAs are encapsidated by the viral Gag protein during virion assembly. The intracellular location of the initial Gag-RNA interaction is unknown. We previously observed feline immunodeficiency virus (FIV) Gag accumulating at the nuclear envelope during live-cell imaging, which suggested that trafficking of human immunodeficiency virus type 1 (HIV-1) and FIV Gag may differ. Here we analyzed the nucleocytoplasmic transport properties of both Gag proteins. We discovered that inhibition of the CRM1 nuclear export pathway with leptomycin B causes FIV Gag but not HIV-1 Gag to accumulate in the nucleus. Virtually all FIV Gag rapidly became intranuclear when the CRM1 export pathway was blocked, implying that most if not all FIV Gag normally undergoes nuclear cycling. In FIV-infected feline cells, some intranuclear Gag was detected in the steady state without leptomycin B treatment. When expressed individually, the FIV matrix (MA), capsid (CA), and nucleocapsid-p2 (NC-p2) domains were not capable of mediating leptomycin B-sensitive nuclear export of a fluorescent protein. In contrast, CA-NC-p2 did mediate nuclear export, with MA being dispensable. We conclude that HIV-1 and FIV Gag differ strikingly in a key intracellular trafficking property. FIV Gag is a nuclear shuttling protein that utilizes the CRM1 nuclear export pathway, while HIV-1 Gag is excluded from the nucleus. These findings expand the spectrum of lentiviral Gag behaviors and raise the possibility that FIV genome encapsidation may initiate in the nucleus.

Download Full-text