scholarly journals Involvement of CRM1, a nuclear export receptor, in mRNA export in mammalian cells and fission yeast

1999 ◽  
Vol 4 (5) ◽  
pp. 291-297 ◽  
Author(s):  
Mina Watanabe ◽  
Makoto Fukuda ◽  
Minoru Yoshida ◽  
Mitsuhiro Yanagida ◽  
Eisuke Nishida
Keyword(s):  
Fission Yeast ◽  
Nuclear Export ◽  
Mammalian Cells ◽  
Mrna Export ◽  
Nuclear Export Receptor

scholarly journals Coordination of Hpr1 and Ubiquitin Binding by the UBA Domain of the mRNA Export Factor Mex67

2007 ◽  
Vol 18 (7) ◽  
pp. 2561-2568 ◽  
Author(s):  
Maria Hobeika ◽  
Christoph Brockmann ◽  
Nahid Iglesias ◽  
Carole Gwizdek ◽  
David Neuhaus ◽  
...  
Keyword(s):  
Substrate Specificity ◽  
Conformational Change ◽  
Nuclear Export ◽  
Transcription Elongation ◽  
Mrna Export ◽  
Molecular Switch ◽  
Ubiquitin Binding ◽  
Uba Domain ◽  
Nuclear Export Receptor

The ubiquitin-associated (UBA) domain of the mRNA nuclear export receptor Mex67 helps in coordinating transcription elongation and nuclear export by interacting both with ubiquitin conjugates and specific targets, such as Hpr1, a component of the THO complex. Here, we analyzed substrate specificity and ubiquitin selectivity of the Mex67 UBA domain. UBA-Mex67 is formed by three helices arranged in a classical UBA fold plus a fourth helix, H4. Deletion or mutation of helix H4 strengthens the interaction between UBA-Mex67 and ubiquitin, but it decreases its affinity for Hpr1. Interaction with Hpr1 is required for Mex67 UBA domain to bind polyubiquitin, possibly by inducing an H4-dependent conformational change. In vivo, deletion of helix H4 reduces cotranscriptional recruitment of Mex67 on activated genes, and it also shows an mRNA export defect. Based on these results, we propose that H4 functions as a molecular switch that coordinates the interaction of Mex67 with ubiquitin bound to specific substrates, defines the selectivity of the Mex67 UBA domain for polyubiquitin, and prevents its binding to nonspecific substrates.

scholarly journals Structural and Functional Analysis of the RNA Transport Element, a Member of an Extensive Family Present in the Mouse Genome

2005 ◽  
Vol 79 (4) ◽  
pp. 2356-2365 ◽  
Author(s):  
Sergey Smulevitch ◽  
Daniel Michalowski ◽  
Andrei S. Zolotukhin ◽  
Ralf Schneider ◽  
Jenifer Bear ◽  
...  
Keyword(s):  
Secondary Structure ◽  
Nuclear Export ◽  
Mammalian Cells ◽  
Minimal Element ◽  
Structural Features ◽  
Rna Transport ◽  
Immunodeficiency Virus ◽  
Responsive Element ◽  
Nuclear Export Receptor ◽  
Intracisternal A Particle

ABSTRACT We previously identified an RNA transport element (RTE), present in a subclass of rodent intracisternal A particle retroelements (F. Nappi, R. Schneider, A. Zolotukhin, S. Smulevitch, D. Michalowski, J. Bear, B. Felber, and G. Pavlakis, J. Virol. 75:4558-4569, 2001), that is able to replace Rev-responsive element regulation in human immunodeficiency virus type 1. RTE-directed mRNA export is mediated by a still-unknown cellular factor(s), is independent of the CRM1 nuclear export receptor, and is conserved among vertebrates. Here we show that this RTE folds into an extended RNA secondary structure and thus does not resemble any known RTEs. Computer searches revealed the presence of 105 identical elements and more than 3,000 related elements which share at least 70% sequence identity with the RTE and which are found on all mouse chromosomes. These related elements are predicted to fold into RTE-like structures. Comparison of the sequences and structures revealed that the RTE and related elements can be divided into four groups. Mutagenesis of the RTE revealed that the minimal element contains four internal stem-loops, which are indispensable for function in mammalian cells. In contrast, only part of the element is essential to mediate RNA transport in microinjected Xenopus laevis oocyte nuclei. Importantly, the minimal RTE able to promote RNA transport has key structural features which are preserved in all the RTE-related elements, further supporting their functional importance. Therefore, RTE function depends on a complex secondary structure that is important for the interaction with the cellular export factor(s).

scholarly journals The prototype γ-2 herpesvirus nucleocytoplasmic shuttling protein, ORF 57, transports viral RNA through the cellular mRNA export pathway

2005 ◽  
Vol 387 (2) ◽  
pp. 295-308 ◽  
Author(s):  
Ben J. L. WILLIAMS ◽  
James R. BOYNE ◽  
Delyth J. GOODWIN ◽  
Louise ROADEN ◽  
Guillaume M. HAUTBERGUE ◽  
...  
Keyword(s):  
Nuclear Export ◽  
Mammalian Cells ◽  
Mrna Export ◽  
Dominant Negative ◽  
Viral Rna ◽  
Exon Junction Complex ◽  
Independent Manner ◽  
Exon Junction ◽  
Export Pathway ◽  
Rna Export

HVS (herpesvirus saimiri) is the prototype γ-2 herpesvirus. This is a subfamily of herpesviruses gaining importance since the identification of the first human γ-2 herpesvirus, Kaposi's sarcoma-associated herpesvirus. The HVS ORF 57 (open reading frame 57) protein is a multifunctional transregulatory protein homologous with genes identified in all classes of herpesviruses. Recent work has demonstrated that ORF 57 has the ability to bind viral RNA, shuttles between the nucleus and cytoplasm and promotes the nuclear export of viral transcripts. In the present study, we show that ORF 57 shuttles between the nucleus and cytoplasm in a CRM-1 (chromosomal region maintenance 1)-independent manner. ORF 57 interacts with the mRNA export factor REF (RNA export factor) and two other components of the exon junction complex, Y14 and Magoh. The association of ORF 57 with REF stimulates recruitment of the cellular mRNA export factor TAP (Tip-associated protein), and HVS infection triggers the relocalization of REF and TAP from the nuclear speckles to several large clumps within the cell. Using a dominant-negative form of TAP and RNA interference to deplete TAP, we show that it is essential for bulk mRNA export in mammalian cells and is required for ORF 57-mediated viral RNA export. Furthermore, we show that the disruption of TAP reduces viral replication. These results indicate that HVS utilizes ORF 57 to recruit components of the exon junction complex and subsequently TAP to promote viral RNA export through the cellular mRNA export pathway.

scholarly journals Cytoplasmic Sequestration of Rel Proteins by IκBα Requires CRM1-Dependent Nuclear Export

2000 ◽  
Vol 20 (6) ◽  
pp. 2269-2284 ◽  
Author(s):  
Winnie F. Tam ◽  
Linda H. Lee ◽  
Laura Davis ◽  
Ranjan Sen
Keyword(s):  
Nuclear Export ◽  
Mammalian Cells ◽  
Regulatory Function ◽  
Main Function ◽  
Cell Cytoplasm ◽  
Leptomycin B ◽  
Major Site ◽  
Cos Cells ◽  
Nuclear Export Receptor ◽  
Nuclear Relocation

ABSTRACT Rel and IκB protein families form a complex cellular regulatory network. A major regulatory function of IκB proteins is to retain Rel proteins in the cell cytoplasm. In addition, IκB proteins have also been postulated to serve nuclear functions. These include the maintenance of inducible NF-κB-dependent gene transcription, as well as termination of inducible transcription. We show that IκBα shuttles between the nucleus and the cytoplasm, utilizing the nuclear export receptor CRM1. A CRM1-binding export sequence was identified in the N-terminal domain of IκBα but not in that of IκBβ or IκBɛ. By reconstituting major aspects of NF-κB–IκB sequestration in yeast, we demonstrate that cytoplasmic retention of p65 (also called RelA) by IκBα requires Crm1p-dependent nuclear export. In mammalian cells, inhibition of CRM1 by leptomycin B resulted in nuclear localization of cotransfected p65 and IκBα in COS cells and enhanced nuclear relocation of endogenous p65 in T cells. These observations suggest that the main function of IκBα is that of a nuclear export chaperone rather than a cytoplasmic tether. We propose that the nucleus is the major site of p65-IκBα association, from where these complexes must be exported in order to create the cytoplasmic pool.

scholarly journals Nuclear Export Through Nuclear Envelope Remodeling inSaccharomyces cerevisiae

2017 ◽  
Author(s):  
Baojin Ding ◽  
Anne M. Mirza ◽  
James Ashley ◽  
Vivian Budnik ◽  
Mary Munson
Keyword(s):  
Nuclear Envelope ◽  
Nuclear Export ◽  
Mammalian Cells ◽  
Budding Yeast ◽  
Mrna Export ◽  
Low Frequency ◽  
Nuclear Pore ◽  
Wild Type ◽  
Export Pathway ◽  
Wild Type Yeast

ABSTRACTIn eukaryotes, subsets of exported mRNAs are organized into large ribonucleoprotein (megaRNP) granules. How megaRNPs exit the nucleus is unclear, as their diameters are much larger than the nuclear pore complex (NPC) central channel. We previously identified a non-canonical nuclear export mechanism inDrosophila(Speese et al.,Cell2012) and mammals (Ding et al., in preparation), in which megaRNPs exit the nucleus by budding across nuclear envelope (NE) membranes. Here, we present evidence for a similar pathway in the nucleus of the budding yeast S.cerevisiae, which contain morphologically similar granules bearing mRNAs. Wild-type yeast displayed these granules at very low frequency, but this frequency was dramatically increased when the non-essential NPC protein Nup116 was deleted. These granules were not artifacts of defective NPCs; a mutation in the exportinXPO1(CRM1), in which NPCs are normal, induced similar megaRNP upregulation. We hypothesize that a non-canonical nuclear export pathway, analogous to those observed inDrosophilaand in mammalian cells, exists in yeast, and that this pathway is upregulated for use when NPCs or nuclear export are impaired.SUMMARYDing et al., describe a non-canonical mRNA export pathway in budding yeast similar to that observed inDrosophila. This pathway appears upregulated when the NPC is impaired, nuclear envelope integrity is disrupted, or the export factor Xpo1 (CRM1) is defective.

Nuclear pore localization and nucleocytoplasmic transport of eIF-5A: evidence for direct interaction with the export receptor CRM1

1999 ◽  
Vol 112 (14) ◽  
pp. 2369-2380 ◽  
Author(s):  
O. Rosorius ◽  
B. Reichart ◽  
F. Kratzer ◽  
P. Heger ◽  
M.C. Dabauvalle ◽  
...  
Keyword(s):  
Nuclear Export ◽  
Mammalian Cells ◽  
Direct Interaction ◽  
Nucleocytoplasmic Transport ◽  
Cellular Protein ◽  
Initiation Factor ◽  
Immunogold Electron Microscopy ◽  
Nuclear Pore ◽  
Nuclear Export Receptor

Eukaryotic initiation factor 5A (eIF-5A) is the only cellular protein known to contain the unusual amino acid hypusine. The exact in vivo function of eIF-5A, however, is to date unknown. The finding that eIF-5A is an essential cofactor of the human immunodeficiency virus type 1 (HIV-1) Rev RNA transport factor suggested that eIF-5A is part of a specific nuclear export pathway. In this study we used indirect immunofluorescence and immunogold electron microscopy to demonstrate that eIF-5A accumulates at nuclear pore-associated intranuclear filaments in mammalian cells and Xenopus oocytes. We are able to show that eIF-5A interacts with the general nuclear export receptor, CRM1. Furthermore, microinjection studies in somatic cells revealed that eIF-5A is transported from the nucleus to the cytoplasm, and that this nuclear export is blocked by leptomycin B. Our data demonstrate that eIF-5A is a nucleocytoplasmic shuttle protein.

scholarly journals The deubiquitylase Ubp15 couples transcription to mRNA export

eLife ◽  
2020 ◽  
Vol 9 ◽  
Author(s):  
Fanny Eyboulet ◽  
Célia Jeronimo ◽  
Jacques Côté ◽  
François Robert
Keyword(s):  
Rna Polymerase Ii ◽  
Nuclear Pore Complex ◽  
Nuclear Export ◽  
Mrna Export ◽  
Nuclear Pore ◽  
Messenger Rnas ◽  
E3 Ligases ◽  
Nuclear Export Receptor ◽  
Nascent Transcripts

Nuclear export of messenger RNAs (mRNAs) is intimately coupled to their synthesis. pre-mRNAs assemble into dynamic ribonucleoparticles as they are being transcribed, processed, and exported. The role of ubiquitylation in this process is increasingly recognized but, while a few E3 ligases have been shown to regulate nuclear export, evidence for deubiquitylases is currently lacking. Here we identified deubiquitylase Ubp15 as a regulator of nuclear export in Saccharomyces cerevisiae. Ubp15 interacts with both RNA polymerase II and the nuclear pore complex, and its deletion reverts the nuclear export defect of E3 ligase Rsp5 mutants. The deletion of UBP15 leads to hyper-ubiquitylation of the main nuclear export receptor Mex67 and affects its association with THO, a complex coupling transcription to mRNA processing and involved in the recruitment of mRNA export factors to nascent transcripts. Collectively, our data support a role for Ubp15 in coupling transcription to mRNA export.

scholarly journals The Deubiquitylase Ubp15 Couples Transcription to mRNA Export

2020 ◽  
Author(s):  
Fanny Eyboulet ◽  
Célia Jeronimo ◽  
Jacques Côté ◽  
François Robert
Keyword(s):  
Rna Polymerase Ii ◽  
Nuclear Pore Complex ◽  
Nuclear Export ◽  
Mrna Export ◽  
Nuclear Pore ◽  
Messenger Rnas ◽  
E3 Ligases ◽  
Nuclear Export Receptor ◽  
Nascent Transcripts

ABSTRACTThe nuclear export of messenger RNAs (mRNAs) is intimately coupled to their synthesis. pre-mRNAs assemble into dynamic ribonucleoparticles as they are being transcribed, processed and exported. The role of ubiquitylation in this process is increasingly recognized as the ubiquitylation of many key players have been shown to affect mRNA nuclear export. While a few E3 ligases have been shown to regulate nuclear export, evidence for deubiquitylases is currently lacking. Here, we identified the deubiquitylase Ubp15 as a regulator of nuclear export in Saccharomyces cerevisiae. Ubp15 interacts both with RNA polymerase II and with the nuclear pore complex, and its deletion reverts the nuclear export defect of mutants of the E3 ligase Rsp5. The deletion of UBP15 leads to hyper-ubiquitylation of the main nuclear export receptor Mex67 and affects its association with THO, a complex coupling transcription to mRNA processing and involved in the recruitment of mRNA export factors to nascent transcripts. Collectively, our data support a role for Ubp15 in coupling transcription to mRNA export.

scholarly journals Mex67p of Schizosaccharomyces pombeInteracts with Rae1p in Mediating mRNA Export

2000 ◽  
Vol 20 (23) ◽  
pp. 8767-8782 ◽  
Author(s):  
Jin Ho Yoon ◽  
Dona C. Love ◽  
Anjan Guhathakurta ◽  
John A. Hanover ◽  
Ravi Dhar
Keyword(s):  
Nuclear Export ◽  
Rna Binding ◽  
Fluorescent Protein ◽  
Synthetic Lethality ◽  
Sequence Similarity ◽  
Mrna Export ◽  
Nuclear Periphery ◽  
Nuclear Pore ◽  
Multicopy Suppressor ◽  
Accessory Factor

ABSTRACT We identified the Schizosaccharomyces pombe mex67 gene (spmex67) as a multicopy suppressor of rae1-167 nup184-1 synthetic lethality and the rae1-167 tsmutation. spMex67p, a 596-amino-acid-long protein, has considerable sequence similarity to the Saccharomyces cerevisiae Mex67p (scMex67p) and human Tap. In contrast toscMEX67, spmex67 is essential for neither growth nor nuclear export of mRNA. However, an spmex67 null mutation (Δmex67) is synthetically lethal with therae1-167 mutation and accumulates poly(A)+ RNA in the nucleus. We identified a central region (149 to 505 amino acids) within spMex67p that associates with a complex containing Rae1p that complements growth and mRNA export defects of therae1-167 Δmex67 synthetic lethality. This region is devoid of RNA-binding, N-terminal nuclear localization, and the C-terminal nuclear pore complex-targeting regions. The (149–505)-green fluorescent protein (GFP) fusion is found diffused throughout the cell. Overexpression of spMex67p inhibits growth and mRNA export and results in the redistribution of the diffused localization of the (149–505)-GFP fusion to the nucleus and the nuclear periphery. These results suggest that spMex67p competes for essential mRNA export factor(s). Finally, we propose that the 149–505 region of spMex67p could act as an accessory factor in Rae1p-dependent transport and that spMex67p participates at various common steps with Rae1p export complexes in promoting the export of mRNA.

Sign in / Sign up

Export Citation Format

Share Document