Nucleic Acids Research Advance Access originally published online on June 22, 2007
Nucleic Acids Research 2007 35(13):4542-4551; doi:10.1093/nar/gkm461
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Nucleic Acids Research, 2007, Vol. 35, No. 13 4542-4551
© 2007 The Author(s)
This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/2.0/uk/) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.
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The abundance of RNPS1, a protein component of the exon junction complex, can determine the variability in efficiency of the Nonsense Mediated Decay pathway
1Department of Pediatric Oncology, Hematology and Immunology, Children's Hospital, University of Heidelberg, Im Neuenheimer Feld 150, 69120 Heidelberg, Germany, 2Molecular Medicine Partnership Unit (University of Heidelberg and European Molecular Biology Laboratory) and 3European Molecular Biology Laboratory, Gene Expression Unit, Meyerhofstr 1, 69117 Heidelberg, Germany
*To whom correspondence should be addressed. Tel: +49 6221 56 2303; Fax: +49 6221 56 4559; Email: andreas.kulozik{at}med.uni-heidelberg.de Correspondence may also be addressed to Matthias W. Hentze. Tel: +49 6221 387 501; Fax: +49 6221 387 518; Email: hentze{at}embl.de
Received February 13, 2007. Revised May 9, 2007. Accepted May 27, 2007.
Nonsense-mediated mRNA decay (NMD) is a molecular pathway of mRNA surveillance that ensures rapid degradation of mRNAs containing premature translation termination codons (PTCs) in eukaryotes. NMD has been shown to also regulate normal gene expression and thus emerged as one of the key post-transcriptional mechanisms of gene regulation. Recently, NMD efficiency has been shown to vary between cell types and individuals thus implicating NMD as a modulator of genetic disease severity. We have now specifically analysed the molecular mechanism of variable NMD efficiency and first established an assay system for the quantification of NMD efficiency, which is based on carefully validated cellular NMD target transcripts. In a HeLa cell model system, NMD efficiency is shown to be remarkably variable and to represent a stable characteristic of different strains. In one of these strains, low NMD efficiency is shown to be functionally related to the reduced abundance of the exon junction component RNPS1. Furthermore, restoration of functional RNPS1 expression, but not of NMD-inactive mutant proteins, also restores efficient NMD in this model. We conclude that cellular concentrations of RNPS1 can modify NMD efficiency and propose that cell type specific co-factor availability represents a novel principle that controls NMD.