A new pathway of translational regulation mediated by eukaryotic initiation factor 3.
We report a new pathway of translation regulation that may operate in interferon-treated or virus-infected mammalian cells. This pathway is activated by P56, a protein whose synthesis is strongly induced by interferons or double-stranded RNA. Using a yeast two-hybrid screen, we identified the P48 subunit of the mammalian translation initiation factor eIF-3 as a protein that interacts with P56. The P56-P48 interaction was confirmed in human cells by co-immunoprecipitation assays and confocal microscopy. Gel filtration assays revealed that P56 binds to the large eIF-3 complex that contains P48. Purified recombinant P56 inhibited in vitro translation of reporter mRNAs in a dose-dependent fashion, and that inhibition was reversed by the addition of purified eIF-3. In vivo, expression of transfected P56 or induction of the endogenous P56 by interferon caused an inhibition of overall cellular protein synthesis and the synthesis of a transfected reporter protein. As expected, a P56 mutant that does not interact with P48 and eIF-3 failed to inhibit protein synthesis in vitro and in vivo.
Guo
J
J
Department of Molecular Biology, The Lerner Research Institute, Cleveland Clinic Foundation, 9500 Euclid Avenue, Cleveland, OH 44195, USA.
Hui
D J
DJ
Merrick
W C
WC
Sen
G C
GC
D048868:Adaptor Proteins, Signal Transducing; D000818:Animals; D001483:Base Sequence; D002352:Carrier Proteins / Q000235:genetics / Q000378:metabolism*; D003001:Cloning, Molecular; D039621:Eukaryotic Initiation Factor-3; D005354:Fibrosarcoma; D005786:Gene Expression Regulation; D017930:Genes, Reporter; D006367:HeLa Cells; D006801:Humans; D008322:Mammals; D008969:Molecular Sequence Data; D010448:Peptide Initiation Factors / Q000378:metabolism*; D014176:Protein Biosynthesis; D021122:Protein Subunits; D012333:RNA, Messenger / Q000235:genetics; D016601:RNA-Binding Proteins; D011994:Recombinant Proteins / Q000378:metabolism; D012441:Saccharomyces cerevisiae; D014162:Transfection; D014407:Tumor Cells, Cultured
D048868:Adaptor Proteins, Signal Transducing; D002352:Carrier Proteins; D039621:Eukaryotic Initiation Factor-3; C484290:IFIT1 protein, human; D010448:Peptide Initiation Factors; D021122:Protein Subunits; D012333:RNA, Messenger; D016601:RNA-Binding Proteins; D011994:Recombinant Proteins