Evidence for a Pioneer Round of mRNA Translation: mRNAs Subject to Nonsense-Mediated Decay in Mammalian Cells Are Bound by CBP80 and CBP20

• Published in: Cell Vol. 106; no. 5; pp. 607 - 617
• Main Authors: Ishigaki, Yasuhito, Li, Xiaojie, Serin, Guillaume, Maquat, Lynne E.
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 07.09.2001
• Subjects: 3T3 Cells; Alpha-Globulins - genetics; Alpha-Globulins - metabolism; Animals; CBP20 protein; CBP80 protein; Cell Nucleus - metabolism; Codon, Nonsense - metabolism; COS Cells; Cross-Linking Reagents - metabolism; Cycloheximide - pharmacology; eIF4E protein; Eukaryotic Initiation Factor-4G; Globins - genetics; Globins - metabolism; Glutathione Peroxidase - genetics; Glutathione Peroxidase - metabolism; Humans; Immunoblotting; Macromolecular Substances; Mice; Models, Biological; nonsense-mediated mRNA decay; Peptide Initiation Factors - genetics; Peptide Initiation Factors - metabolism; Poly(A)-Binding Proteins; Protein Biosynthesis; Protein Synthesis Inhibitors - pharmacology; Proteins; Reverse Transcriptase Polymerase Chain Reaction; RNA Cap-Binding Proteins; RNA Caps - metabolism; RNA, Messenger - genetics; RNA, Messenger - metabolism; RNA-Binding Proteins - metabolism; Transfection; Upf2 protein; Upf3 protein
• ISSN: 0092-8674; 1097-4172
• DOI: 10.1016/S0092-8674(01)00475-5

Nonsense-mediated decay (NMD) eliminates mRNAs that prematurely terminate translation. We used antibody to the nuclear cap binding protein CBP80 or its cytoplasmic counterpart eIF4E to immunopurify RNP containing nonsense-free or nonsense-containing transcripts. Data indicate that NMD takes place in association with CBP80. We defined other components of NMD-susceptible mRNP as CBP20, PABP2, eIF4G, and the NMD factors Upf2 and Upf3. Consistent with the dependence of NMD on translation, the NMD of CBP80-bound mRNA is blocked by cycloheximide or suppressor tRNA. These findings provide evidence that translation can take place in association with CBP80. They also indicate that CBP80-bound mRNA undergoes a “pioneer” round of translation, before CBP80-CBP20 are replaced by eIF4E, and Upf2 and Upf3 proteins dissociate from upstream of exon-exon junctions.