title: 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.affiliation: Department of Cellular and Molecular Medicine, Faculty of Medicine, University of Ottawa, Ottawa, Ontario, K1H 8M5, Canada.
authors.forename: Mireille
authors.initials: M
authors.lastname: Khacho
authors.forename: Karim
authors.initials: K
authors.lastname: Mekhail
authors.forename: Karine
authors.initials: K
authors.lastname: Pilon-Larose
authors.forename: Arnim
authors.initials: A
authors.lastname: Pause
authors.forename: Jocelyn
authors.initials: J
authors.lastname: Côté
authors.forename: Stephen
authors.initials: S
authors.lastname: Lee
mesh_terms: D021581:Active Transport, Cell Nucleus / Q000502:physiology*; D000818:Animals; D002460:Cell Line; D002467:Cell Nucleus / Q000378:metabolism* / Q000648:ultrastructure; D006801:Humans; D009685:Nuclear Envelope / Q000378:metabolism; D049790:Nuclear Export Signals / Q000235:genetics*; D020648:Peptide Elongation Factor 1 / Q000235:genetics / Q000378:metabolism*; D039122:Poly(A)-Binding Protein I / Q000235:genetics / Q000378:metabolism; D034741:RNA, Small Interfering / Q000235:genetics / Q000378:metabolism; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D051794:Von Hippel-Lindau Tumor Suppressor Protein / Q000235:genetics / Q000378:metabolism
chemical_list: D049790:Nuclear Export Signals; D020648:Peptide Elongation Factor 1; D039122:Poly(A)-Binding Protein I; D034741:RNA, Small Interfering; D011993:Recombinant Fusion Proteins; D051794:Von Hippel-Lindau Tumor Suppressor Protein
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