Ectopic expression of eIF4E-transporter triggers the movement of eIF4E into P-bodies, inhibiting steady-state translation but not the pioneer round of translation.
Nonsense-mediated mRNA decay (NMD) is the best-characterized mRNA surveillance mechanism; this process removes faulty mRNAs harboring premature termination codons (PTCs). NMD targets newly synthesized mRNAs bound by nuclear cap-binding proteins 80/20 (CBP80/20) and exon junction complex (EJC), the former of which is thought to recruit the ribosome to initiate the pioneer round of translation. After completion of the pioneer round of translation, CBP80/20 is replaced by the cytoplasmic cap-binding protein eIF4E, which mediates steady-state translation in the cytoplasm. Here, we show that overexpression of eIF4E-T preferentially inhibits cap-dependent steady-state translation, but not the pioneer round of translation. We also demonstrate that overexpression of eIF4E-T or Dcp1a triggers the movement of eIF4E into the processing bodies. These results suggest that the pioneer round of translation differs from steady-state translation in terms of ribosome recruitment.
Lee
Hyung Chul
HC
School of Life Sciences and Biotechnology, Korea University, Anam-Dong, Seongbuk-Gu, Seoul 136-701, Republic of Korea.
Cho
Hana
H
Kim
Yoon Ki
YK
D004722:Endoribonucleases / Q000235:genetics / Q000378:metabolism; D039561:Eukaryotic Initiation Factor-4E / Q000378:metabolism*; D006367:HeLa Cells; D006801:Humans; D039502:Nuclear Cap-Binding Protein Complex / Q000378:metabolism; D029543:Nucleocytoplasmic Transport Proteins / Q000235:genetics / Q000378:metabolism*; D014176:Protein Biosynthesis; D012315:RNA Caps / Q000378:metabolism*; D020871:RNA Stability; D015534:Trans-Activators / Q000235:genetics / Q000378:metabolism
C411571:EIF4ENIF1 protein, human; D039561:Eukaryotic Initiation Factor-4E; D039502:Nuclear Cap-Binding Protein Complex; D029543:Nucleocytoplasmic Transport Proteins; D012315:RNA Caps; D015534:Trans-Activators; D004722:Endoribonucleases; C466279:DCP1A protein, human