Faculty Opinions recommendation of REF1/Aly and the additional exon junction complex proteins are dispensable for nuclear mRNA export.

2003 ◽  
Author(s):  
Thomas Blumenthal
Keyword(s):  
Mrna Export ◽  
Exon Junction Complex ◽  
Exon Junction ◽  
Additional Exon

scholarly journals REF1/Aly and the additional exon junction complex proteins are dispensable for nuclear mRNA export

2002 ◽  
Vol 159 (4) ◽  
pp. 579-588 ◽  
Author(s):  
David Gatfield ◽  
Elisa Izaurralde
Keyword(s):  
Essential Role ◽  
Mrna Export ◽  
Adaptor Protein ◽  
Protein S ◽  
Nuclear Accumulation ◽  
Nuclear Pore ◽  
Exon Junction Complex ◽  
Exon Junction ◽  
Cellular Mrnas ◽  
Additional Exon

The metazoan proteins UAP56, REF1, and NXF1 are thought to bind sequentially to mRNA to promote its export to the cytoplasm: UAP56 is thought to recruit REF1 to nascent mRNA; REF1 acts as an adaptor protein mediating the association of NXF1 with mRNA, whereas NXF1 translocates the mRNA across the nuclear pore complex. REF1 is a component of the exon–exon junction complex (EJC); thus, the EJC is thought to play a role in the export of spliced mRNA. NXF1 and UAP56 are essential for mRNA export. An essential role for metazoan REF1 or the additional EJC proteins in this process has not been established. Contrary to expectation, we show that REF1 and the additional components of the EJC are dispensable for export of bulk mRNA in Drosophila cells. Only when REF1 and RNPS1 are codepleted, or when all EJC proteins are simultaneously depleted is a partial nuclear accumulation of polyadenylated RNAs observed. Because a significant fraction of bulk mRNA is detected in the cytoplasm of cells depleted of all EJC proteins, we conclude that additional adaptor protein(s) mediate the interaction between NXF1 and cellular mRNAs in metazoa. Our results imply that the essential role of UAP56 in mRNA export is not restricted to the recruitment of REF1.

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 A Day in the Life of the Exon Junction Complex

Biomolecules ◽  
2020 ◽  
Vol 10 (6) ◽  
pp. 866 ◽  
Author(s):  
Lena P. Schlautmann ◽  
Niels H. Gehring
Keyword(s):  
Mrna Export ◽  
Mrna Splicing ◽  
Exon Junction Complex ◽  
Chronological Order ◽  
Exon Junction ◽  
Messenger Ribonucleoprotein ◽  
Associated Proteins ◽  
Core Components ◽  
Nonsense Mediated Mrna Decay ◽  
Exon Junctions

The exon junction complex (EJC) is an abundant messenger ribonucleoprotein (mRNP) component that is assembled during splicing and binds to mRNAs upstream of exon-exon junctions. EJCs accompany the mRNA during its entire life in the nucleus and the cytoplasm and communicate the information about the splicing process and the position of introns. Specifically, the EJC’s core components and its associated proteins regulate different steps of gene expression, including pre-mRNA splicing, mRNA export, translation, and nonsense-mediated mRNA decay (NMD). This review summarizes the most important functions and main protagonists in the life of the EJC. It also provides an overview of the latest findings on the assembly, composition and molecular activities of the EJC and presents them in the chronological order, in which they play a role in the EJC’s life cycle.

The exon junction complex: structural insights into a faithful companion of mammalian mRNPs

2018 ◽  
Vol 46 (1) ◽  
pp. 153-161 ◽  
Author(s):  
Jennifer V. Gerbracht ◽  
Niels H. Gehring
Keyword(s):  
Essential Role ◽  
Mrna Export ◽  
Physiological Data ◽  
Exon Junction Complex ◽  
Interacting Proteins ◽  
Exon Junction ◽  
Comprehensive Picture ◽  
Complex Structural ◽  
Structural Insights ◽  
Insight Into

During splicing, the exon junction complex (EJC) is deposited upstream of exon-exon boundaries. The EJC and its peripheral bound proteins play an essential role in mediating mRNA export, translation and turnover. However, the exact sequence of EJC assembly and the involved factors during splicing remain elusive. Recently published structures of the human C* spliceosome clarified the position of the EJC at this phase of splicing and have given insight into previously unidentified interactions between the EJC and spliceosomal proteins. Here, these new observations are presented and the significance for EJC assembly is discussed. Furthermore, the vast landscape of EJC interacting proteins and their manifold functions are described. Finally, the factors involved in EJC disassembly and recycling are recapitulated. This review aims to integrate structural, biochemical and physiological data to obtain a comprehensive picture of EJC components during the lifetime of the EJC.

Sign in / Sign up

Export Citation Format

Share Document