Exon-junction complex components specify distinct routes of nonsense-mediated mRNA decay with differential cofactor requirements.
Messenger RNAs (mRNAs) bearing premature translation termination codons (PTCs) are degraded by nonsense-mediated mRNA decay (NMD). For mammalian NMD, current models propose a linear pathway that involves the splicing-dependent deposition of exon-junction complexes (EJCs) and the sequential action of the NMD factors UPF3, UPF2, and UPF1. We show here that different EJC proteins serve as entry points for the formation of distinguishable NMD-activating mRNPs. Specifically, Y14, MAGOH, and eIF4A3 can activate NMD in an UPF2-independent manner, whereas RNPS1-induced NMD requires UPF2. We identify the relevant regions of RNPS1, eIF4A3, Y14, and MAGOH, which are essential for NMD and provide insights into the formation of complexes, that classify alternative NMD pathways. These results are integrated into a nonlinear model for mammalian NMD involving alternative routes of entry that converge at a common requirement of UPF1.
Gehring
Niels H
NH
Molecular Medicine Partnership Unit, University of Heidelberg and European Molecular Biology Laboratory, Heidelberg 69120, Germany.
Kunz
Joachim B
JB
Neu-Yilik
Gabriele
G
Breit
Stephen
S
Viegas
Marcelo H
MH
Hentze
Matthias W
MW
Kulozik
Andreas E
AE
D000818:Animals; D018389:Codon, Nonsense / Q000235:genetics / Q000378:metabolism; D005091:Exons / Q000502:physiology*; D005786:Gene Expression Regulation / Q000502:physiology; D006367:HeLa Cells; D006801:Humans; D008954:Models, Biological; D046912:Multiprotein Complexes / Q000378:metabolism; D012326:RNA Splicing / Q000502:physiology*; D020871:RNA Stability / Q000502:physiology*; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism*; D012261:Ribonucleoproteins / Q000235:genetics / Q000378:metabolism; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism
D018389:Codon, Nonsense; D046912:Multiprotein Complexes; D012333:RNA, Messenger; C084538:RNPS1 protein, human; D012261:Ribonucleoproteins; D014157:Transcription Factors