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Nuclear Eukaryotic Initiation Factor 4e (Eif4e) Colocalizes with Splicing Factors in Speckles

The eukaryotic initiation factor 4E (eIF4E) plays a pivotal role in the control of protein synthesis. eIF4E binds to the mRNA 5′ cap structure, m(7)GpppN (where N is any nucleotide) and promotes ribosome binding to the mRNA. It was previously shown that a fraction of eIF4E localizes to the nucleus (...

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Autores principales: Dostie, Josée, Lejbkowicz, Flavio, Sonenberg, Nahum
Formato: Texto
Lenguaje:English
Publicado: The Rockefeller University Press 2000
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2174286/
https://www.ncbi.nlm.nih.gov/pubmed/10648556
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author Dostie, Josée
Lejbkowicz, Flavio
Sonenberg, Nahum
author_facet Dostie, Josée
Lejbkowicz, Flavio
Sonenberg, Nahum
author_sort Dostie, Josée
collection PubMed
description The eukaryotic initiation factor 4E (eIF4E) plays a pivotal role in the control of protein synthesis. eIF4E binds to the mRNA 5′ cap structure, m(7)GpppN (where N is any nucleotide) and promotes ribosome binding to the mRNA. It was previously shown that a fraction of eIF4E localizes to the nucleus (Lejbkowicz, F., C. Goyer, A. Darveau, S. Neron, R. Lemieux, and N. Sonenberg. 1992. Proc. Natl. Acad. Sci. USA. 89:9612–9616). Here, we show that the nuclear eIF4E is present throughout the nucleoplasm, but is concentrated in speckled regions. Double label immunofluorescence confocal microscopy shows that eIF4E colocalizes with Sm and U1snRNP. We also demonstrate that eIF4E is specifically released from the speckles by the cap analogue m(7)GpppG in a cell permeabilization assay. However, eIF4E is not released from the speckles by RNase A treatment, suggesting that retention of eIF4E in the speckles is not RNA-mediated. 5,6-dichloro-1-β-d-ribofuranosylbenzimidazole (DRB) treatment of cells causes the condensation of eIF4E nuclear speckles. In addition, overexpression of the dual specificity kinase, Clk/Sty, but not of the catalytically inactive form, results in the dispersion of eIF4E nuclear speckles.
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spelling pubmed-21742862008-05-01 Nuclear Eukaryotic Initiation Factor 4e (Eif4e) Colocalizes with Splicing Factors in Speckles Dostie, Josée Lejbkowicz, Flavio Sonenberg, Nahum J Cell Biol Brief Report The eukaryotic initiation factor 4E (eIF4E) plays a pivotal role in the control of protein synthesis. eIF4E binds to the mRNA 5′ cap structure, m(7)GpppN (where N is any nucleotide) and promotes ribosome binding to the mRNA. It was previously shown that a fraction of eIF4E localizes to the nucleus (Lejbkowicz, F., C. Goyer, A. Darveau, S. Neron, R. Lemieux, and N. Sonenberg. 1992. Proc. Natl. Acad. Sci. USA. 89:9612–9616). Here, we show that the nuclear eIF4E is present throughout the nucleoplasm, but is concentrated in speckled regions. Double label immunofluorescence confocal microscopy shows that eIF4E colocalizes with Sm and U1snRNP. We also demonstrate that eIF4E is specifically released from the speckles by the cap analogue m(7)GpppG in a cell permeabilization assay. However, eIF4E is not released from the speckles by RNase A treatment, suggesting that retention of eIF4E in the speckles is not RNA-mediated. 5,6-dichloro-1-β-d-ribofuranosylbenzimidazole (DRB) treatment of cells causes the condensation of eIF4E nuclear speckles. In addition, overexpression of the dual specificity kinase, Clk/Sty, but not of the catalytically inactive form, results in the dispersion of eIF4E nuclear speckles. The Rockefeller University Press 2000-01-24 /pmc/articles/PMC2174286/ /pubmed/10648556 Text en © 2000 The Rockefeller University Press This article is distributed under the terms of an Attribution–Noncommercial–Share Alike–No Mirror Sites license for the first six months after the publication date (see http://www.rupress.org/terms). After six months it is available under a Creative Commons License (Attribution–Noncommercial–Share Alike 4.0 Unported license, as described at http://creativecommons.org/licenses/by-nc-sa/4.0/).
spellingShingle Brief Report
Dostie, Josée
Lejbkowicz, Flavio
Sonenberg, Nahum
Nuclear Eukaryotic Initiation Factor 4e (Eif4e) Colocalizes with Splicing Factors in Speckles
title Nuclear Eukaryotic Initiation Factor 4e (Eif4e) Colocalizes with Splicing Factors in Speckles
title_full Nuclear Eukaryotic Initiation Factor 4e (Eif4e) Colocalizes with Splicing Factors in Speckles
title_fullStr Nuclear Eukaryotic Initiation Factor 4e (Eif4e) Colocalizes with Splicing Factors in Speckles
title_full_unstemmed Nuclear Eukaryotic Initiation Factor 4e (Eif4e) Colocalizes with Splicing Factors in Speckles
title_short Nuclear Eukaryotic Initiation Factor 4e (Eif4e) Colocalizes with Splicing Factors in Speckles
title_sort nuclear eukaryotic initiation factor 4e (eif4e) colocalizes with splicing factors in speckles
topic Brief Report
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2174286/
https://www.ncbi.nlm.nih.gov/pubmed/10648556
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