Mechanistic aspects of NMD in human cells

Mühlemann, Oliver (8 September 2013). Mechanistic aspects of NMD in human cells (Unpublished). In: EMBL Conference on Protein Synthesis and Translational Control. EMBL, Heidelberg, Germany. 08.-12.09.2013.

Eukaryotic mRNAs with premature translation termination codons (PTCs) are recognized and degraded through a process termed nonsense-mediated mRNA decay (NMD). To get more insight into the recruitment of the central NMD factor UPF1 to target mRNAs, we mapped transcriptome-wide UPF1-binding sites by individual-nucleotide-resolution UV cross-linking and immunoprecipitation (iCLIP) in human cells and found that UPF1 preferentially associated with 3′ UTRs in translationally active cells but underwent significant redistribution toward coding regions (CDS) upon translation inhibition. This indicates that UPF1 binds RNA before translation and gets displaced from the CDS by translating ribosomes. Corroborated by RNA immunoprecipitation and by UPF1 cross-linking to long noncoding RNAs, our evidence for translation-independent UPF1-RNA interaction suggests that the triggering of NMD occurs after UPF1 binding to mRNA, presumably through activation of RNA-bound UPF1 by aberrant translation termination. Unlike in yeast, in mammalian cells NMD has been reported to be restricted to cap-binding complex (CBC)–bound mRNAs during the pioneer round of translation. However, we compared decay kinetics of two NMD reporter genes in mRNA fractions bound to either CBC or the eukaryotic initiation factor 4E (eIF4E) in human cells and show that NMD destabilizes eIF4E-bound transcripts as efficiently as those associated with CBC. These results corroborate an emerging unified model for NMD substrate recognition, according to which NMD can ensue at every aberrant translation termination event.

Item Type:

Conference or Workshop Item (Speech)

Division/Institute:

08 Faculty of Science > Departement of Chemistry and Biochemistry

UniBE Contributor:

Mühlemann, Oliver

Subjects:

500 Science > 570 Life sciences; biology
500 Science > 540 Chemistry

Language:

English

Submitter:

Christina Schüpbach

Date Deposited:

04 Aug 2014 17:22

Last Modified:

04 Aug 2014 17:22

URI:

https://boris.unibe.ch/id/eprint/55165

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