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Critical Reviews™ in Eukaryotic Gene Expression
Facteur d'impact: 1.734 Facteur d'impact sur 5 ans: 1.848 SJR: 0.627 SNIP: 0.516 CiteScore™: 1.96

ISSN Imprimer: 1045-4403
ISSN En ligne: 2162-6502

Critical Reviews™ in Eukaryotic Gene Expression

DOI: 10.1615/CritRevEukarGeneExpr.v9.i3-4.60
pages 213-219

Intranuclear Trafficking of Messenger RNA

Maria Carmo-Fonseca
Institute of Histology and Embryology, Faculty of Medicine, University of Lisbon, 1649-028 Lisboa Codex, Portugal
Noelia Custodio
Institute of Histology and Embryology, Faculty of Medicine, University of Lisbon, 1649-028 Lisboa Codex, Portugal
Angelo Calado
Institute of Histology and Embryology, Faculty of Medicine, University of Lisbon, 1649-028 Lisboa Codex, Portugal

RÉSUMÉ

Within the nucleus, protein-encoding genes are transcribed into messenger RNA by RNA polymerase II. Messenger RNAs migrate to the cytoplasm, but before reaching their final destination the primary transcripts must undergo a series of modifications that include 5′-capping, splicing, and 3′-cleavage/polyadenylation. Errors in these processing events can originate aberrant products that, if translated, would produce abnormal proteins. Therefore, it is not surprising that eukaryotes have evolved a surveillance mechanism that recognizes and rapidly degrades aberrant mRNAs. Recent experiments provide exciting insights into how proper mRNAs are distinguished and selected for export. Transcription by RNA polymerase II is directly coupled to pre-mRNA processing, and the mechanism that targets the processing machinery to the polymerase complex suggests a model for co-transcriptional proofreading. Furthermore, there is evidence that at least some mRNAs move randomly throughout the nucleus, presumably by free diffusion. In this light, retention of aberrant mRNAs by the transcription/processing machinery is crucial to prevent their diffusion to the nuclear pores and eventual translocation to the cytoplasm.