title: Failsafe nonsense-mediated mRNA decay does not detectably target eIF4E-bound mRNA.
abstract: Nonsense-mediated mRNA decay (NMD) generally eliminates messenger RNAs that prematurely terminate translation and occurs in all eukaryotes that have been studied, although with mechanistic variations. In mammals, NMD seems to be restricted to newly synthesized mRNA that is bound by the cap-binding heterodimer CBP80-CBP20 (CBP80/20) and typically has at least one exon junction complex (EJC) situated downstream of the nonsense codon and added post-splicing. However, mammalian NMD can also target spliced mRNA lacking an EJC downstream of the nonsense codon. Here we provide evidence that this additional pathway, known as failsafe NMD, likewise seems to be restricted to CBP80/20-bound mRNA and does not detectably target its subsequently remodeled product, eIF4E-bound mRNA. Our studies, including analyses of factor dependence, reveal important shared features of the two mammalian-cell NMD pathways as well as fundamental differences between NMD in mammals and Saccharomyces cerevisiae.
authors.affiliation: Department of Biochemistry and Biophysics, School of Medicine and Dentistry, University of Rochester, 601 Elmwood Avenue, Box 712, Rochester, New York 14642, USA.
authors.forename: Daiki
authors.initials: D
authors.lastname: Matsuda
authors.forename: Nao
authors.initials: N
authors.lastname: Hosoda
authors.forename: Yoon Ki
authors.initials: YK
authors.lastname: Kim
authors.forename: Lynne E
authors.initials: LE
authors.lastname: Maquat
mesh_terms: D000818:Animals; D002460:Cell Line; D018389:Codon, Nonsense; D019281:Dimerization; D039561:Eukaryotic Initiation Factor-4E / Q000378:metabolism*; D006801:Humans; D039502:Nuclear Cap-Binding Protein Complex / Q000235:genetics / Q000378:metabolism; D020871:RNA Stability; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism*
chemical_list: D018389:Codon, Nonsense; D039561:Eukaryotic Initiation Factor-4E; D039502:Nuclear Cap-Binding Protein Complex; D012333:RNA, Messenger