RNA Export through the NPC in Eukaryotes

Abstract

In eukaryotic cells, RNAs are transcribed in the nucleus and exported to the cytoplasm through the nuclear pore complex. The RNA molecules that are exported from the nucleus into the cytoplasm include messenger RNAs (mRNAs), ribosomal RNAs (rRNAs), transfer RNAs (tRNAs), small nuclear RNAs (snRNAs), micro RNAs (miRNAs), and viral mRNAs. Each RNA is transported by a specific nuclear export receptor. It is believed that most of the mRNAs are exported by Nxf1 (Mex67 in yeast), whereas rRNAs, snRNAs, and a certain subset of mRNAs are exported in a Crm1/Xpo1-dependent manner. tRNAs and miRNAs are exported by Xpot and Xpo5. However, multiple export receptors are involved in the export of some RNAs, such as 60S ribosomal subunit. In addition to these export receptors, some adapter proteins are required to export RNAs. The RNA export system of eukaryotic cells is also used by several types of RNA virus that depend on the machineries of the host cell in the nucleus for replication of their genome, therefore this review describes the RNA export system of two representative viruses. We also discuss the NPC anchoring-dependent mRNA export factors that directly recruit specific genes to the NPC.

Interleukin 1β Regulation of the System xc− Substrate-specific Subunit, xCT, in Primary Mouse Astrocytes Involves the RNA-binding Protein HuR

“…2). This would be expected because, in addition to its role in mRNA stabilization, HuR is necessary for the export of adenine-and uridine-rich element-containing mRNAs from the nucleus to the cytosol (67,68). Our finding that HuR was bound directly to Slc7a11 mRNA in the polysomal fraction of the cytosol and that this was dependent on IL-1␤ strengthens this conclusion (Fig.…”

Comparative interactomics provides evidence for functional specialization of the nuclear pore complex

“…This suggests that unlike in opisthokonts and plants, GTP and not ATP powers mRNA export in trypanosomes. Interestingly, non protein coding RNA in opisthokonts, such as tRNAs, small nuclear RNAs, micro RNAs and preribosomal subunits, are exported out of the nucleus on a Ran gradient by karyopherins, similar to protein export (reviewed in 47,56 ). Additionally, a small subset of mRNA export is dependent on the karyopherin, Exportin 1 (Crm1).…”

Nucleocytoplasmic Transport of RNAs and RNA–Protein Complexes

“…Recent structural studies have revealed aspects of the mechanisms employed by transport receptors to enable specific cargo recognition, and genome-wide approaches have provided the first insights into the diverse composition of pre-mRNPs during export. Furthermore, the regulation of RNA/RNP export is emerging as an important means to modulate gene expression in stress conditions and disease.The compartmentalisation of eukaryotic cells into nucleus and cytoplasm allows the spatial separation of different steps in gene expression into nuclear events such as transcription, RNA processing and splicing, and cytoplasmic translation [1,2]. However, such separation necessitates the nucleocytoplasmic transport of various biogenesis intermediates, mature RNAs and ribonucleoprotein complexes (RNPs), including messenger (m)RNPs, transfer (t)RNAs, small nuclear (sn)RNPs, micro (mi)RNPs and ribosomal subunits, which are transported as precursors during their biogenesis or in their mature form.…”

“…The compartmentalisation of eukaryotic cells into nucleus and cytoplasm allows the spatial separation of different steps in gene expression into nuclear events such as transcription, RNA processing and splicing, and cytoplasmic translation [1,2]. However, such separation necessitates the nucleocytoplasmic transport of various biogenesis intermediates, mature RNAs and ribonucleoprotein complexes (RNPs), including messenger (m)RNPs, transfer (t)RNAs, small nuclear (sn)RNPs, micro (mi)RNPs and ribosomal subunits, which are transported as precursors during their biogenesis or in their mature form.…”