Interaction of eIF4G with poly(A)-binding protein stimulates translation and is critical for Xenopus oocyte maturation.
The poly(A)-binding protein Pab1p interacts directly with the eukaryotic translation initiation factor 4G (eIF4G) to facilitate translation initiation of polyadenylated mRNAs in yeast [1,2]. Although the eIF4G-PABP interaction has also been demonstrated in a mammalian system [3,4], its biological significance in vertebrates is unknown. In Xenopus oocytes, cytoplasmic polyadenylation of several mRNAs coincides with their translational activation and is critical for maturation [5-7]. Because the amount of PABP is very low in oocytes [8], it has been argued that the eIF4G-PABP interaction does not play a major role in translational activation during oocyte maturation. Also, overexpression of PABP in Xenopus oocytes has only a modest stimulatory effect on translation of polyadenylated mRNA and does not alter either the efficiency or the kinetics of progesterone-induced maturation [9]. Here, we report that the expression of an eIF4GI mutant defective in PABP binding in Xenopus oocytes reduces translation of polyadenylated mRNA and dramatically inhibits progesterone-induced maturation. Our results show that the eIF4G-PABP interaction is critical for translational control of maternal mRNAs during Xenopus development.
Wakiyama
M
M
Department of Biochemistry and McGill Cancer Center, McGill University, Montreal, H3G 1Y6, Quebec, Canada.
Imataka
H
H
Sonenberg
N
N
D000595:Amino Acid Sequence; D019943:Amino Acid Substitution; D000818:Animals; D015153:Blotting, Western; D039603:Eukaryotic Initiation Factor-4G; D016258:Genes, mos / Q000235:genetics; D006801:Humans; D008156:Luciferases / Q000378:metabolism; D008845:Microinjections; D008969:Molecular Sequence Data; D009865:Oocytes / Q000187:drug effects / Q000254:growth & development*; D010448:Peptide Initiation Factors / Q000235:genetics / Q000378:metabolism*; D039102:Poly(A)-Binding Proteins; D011374:Progesterone / Q000494:pharmacology; D014176:Protein Biosynthesis / Q000235:genetics*; D012333:RNA, Messenger / Q000378:metabolism; D016601:RNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D014981:Xenopus / Q000196:embryology
D039603:Eukaryotic Initiation Factor-4G; D010448:Peptide Initiation Factors; D039102:Poly(A)-Binding Proteins; D012333:RNA, Messenger; D016601:RNA-Binding Proteins; D011374:Progesterone; D008156:Luciferases