eEF1A is a novel component of the mammalian nuclear protein export machinery.

Abstract

The cytoplasmic translation factor eEF1A has been implicated in the nuclear export of tRNA species in lower eukaryotes. Here we demonstrate that eEF1A plays a central role in nuclear export of proteins in mammalian cells. TD-NEM (transcription-dependent nuclear export motif), a newly characterized nuclear export signal, mediates efficient nuclear export of several proteins including the von Hippel-Lindau (VHL) tumor suppressor and the poly(A)-binding protein (PABP1) in a manner that is dependent on ongoing RNA polymerase II (RNA PolII)-dependent transcription. eEF1A interacts specifically with TD-NEM of VHL and PABP1 and disrupting this interaction, by point mutations of key TD-NEM residues or treatment with actinomycin D, an inhibitor of RNA PolII-dependent transcription, prevents assembly and nuclear export. siRNA-induced knockdown or antibody-mediated depletion of eEF1A prevents in vivo and in vitro nuclear export of TD-NEM-containing proteins. Nuclear retention experiments and inhibition of the Exportin-5 pathway suggest that eEF1A stimulates nuclear export of proteins from the cytoplasmic side of the nuclear envelope, without entering the nucleus. Together, these data identify a role for eEF1A, a cytoplasmic mediator of tRNA export in yeast, in the nuclear export of proteins in mammalian cells. These results also provide a link between the translational apparatus and subcellular trafficking machinery demonstrating that these two central pathways in basic metabolism can act cooperatively.

• Authors: Mireille Khacho, Karim Mekhail, Karine Pilon-Larose, Arnim Pause, Jocelyn Côté, Stephen Lee
• Journal: Molecular biology of the cell (Mol Biol Cell) Vol. 19 Issue 12 Pg. 5296-308 (Dec 2008) ISSN: 1939-4586 [Electronic] United States
• PMID: 18799616 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)

Chemical References

• Nuclear Export Signals
• Peptide Elongation Factor 1
• Poly(A)-Binding Protein I
• RNA, Small Interfering
• Recombinant Fusion Proteins
• Von Hippel-Lindau Tumor Suppressor Protein

Topics

• Active Transport, Cell Nucleus (physiology)
• Animals
• Cell Line
• Cell Nucleus (metabolism, ultrastructure)
• Humans
• Nuclear Envelope (metabolism)
• Nuclear Export Signals (genetics)
• Peptide Elongation Factor 1 (genetics, metabolism)
• Poly(A)-Binding Protein I (genetics, metabolism)
• RNA, Small Interfering (genetics, metabolism)
• Recombinant Fusion Proteins (genetics, metabolism)
• Von Hippel-Lindau Tumor Suppressor Protein (genetics, metabolism)