A family of insulin-like growth factor II mRNA-binding proteins represses translation in late development
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Insulin-like growth factor II (IGF-II) is a major fetal growth factor. The IGF-II gene generates multiple mRNAs with different 5' untranslated regions (5' UTRs) that are translated in a differential manner during development. We have identified a human family of three IGF-II mRNA-binding proteins (IMPs) that exhibit multiple attachments to the 5' UTR from the translationally regulated IGF-II leader 3 mRNA but are unable to bind to the 5' UTR from the constitutively translated IGF-II leader 4 mRNA. IMPs contain the unique combination of two RNA recognition motifs and four hnRNP K homology domains and are homologous to the Xenopus Vera and chicken zipcode-binding proteins. IMP localizes to subcytoplasmic domains in a growth-dependent and cell-specific manner and causes a dose-dependent translational repression of IGF-II leader 3 -luciferase mRNA. Mouse IMPs are produced in a burst at embryonic day 12.5 followed by a decline towards birth, and, similar to IGF-II, IMPs are especially expressed in developing epithelia, muscle, and placenta in both mouse and human embryos. The results imply that cytoplasmic 5' UTR-binding proteins control IGF-II biosynthesis during late mammalian development.
|Journal||Molecular and Cellular Biology|
|Number of pages||9|
|Publication status||Published - 1999|
- 3T3 Cells, Amino Acid Sequence, Animals, Binding Sites, Cell Line, Chickens, Cloning, Molecular, DNA, Complementary, Embryonic and Fetal Development, Gene Expression Regulation, Developmental, Humans, Insulin-Like Growth Factor II, Mice, Molecular Sequence Data, Protein Biosynthesis, RNA, Messenger, RNA-Binding Proteins, Sequence Homology, Amino Acid, Xenopus