RRC ID 41602
Author Shiroki K, Ohsawa C, Sugi N, Wakiyama M, Miura K, Watanabe M, Suzuki Y, Sugano S.
Title Internal ribosome entry site-mediated translation of Smad5 in vivo: requirement for a nuclear event.
Journal Nucleic Acids Res
Abstract Smad5 is thought to relay signals of the bone morphogenetic protein pathway. The 5' untranslated region (5'UTR) of human Smad5 mRNA is long, has the potential to form secondary structures and contains five AUG codons. Here we show that the 5'UTR of Smad5 contains an internal ribosome entry site (IRES) located within 100 nt of the 3' end of the 5'UTR. The Smad5 IRES was 4-8-fold more active than the poliovirus IRES in C2C12 cells, which have osteoblastic differentiation ability, but was 5-10-fold less active than the poliovirus IRES in 293T cells. When an in vitro transcript of a dicistronic Smad5 IRES construct was transfected into C2C12 cells, the Smad5 IRES was not able to stimulate the translation of the downstream cistron, although the cap-dependent translation of the upstream cistron was efficient. In contrast, the poliovirus IRES in a dicistronic in vitro transcript was able to stimulate the translation of the downstream cistron to a similar extent as in the case of transfection of the corresponding dicistronic DNA construct. These results suggest that Smad5 IRES activity displays cell specificity and that some as yet unidentified nuclear event may be required for efficient Smad5 IRES-driven translation initiation.
Volume 30(13)
Pages 2851-61
Published 2002-7-1
DOI 10.1093/nar/gkf408
PMID 12087169
PMC PMC117063
MeSH 3T3 Cells 5' Untranslated Regions / genetics 5' Untranslated Regions / metabolism Animals Binding Sites / genetics Cell Differentiation Cell Line Cell Nucleus / genetics Cell Nucleus / metabolism DNA-Binding Proteins / genetics* Female HeLa Cells Humans Luciferases / genetics Luciferases / metabolism Mice Oocytes Osteoblasts / cytology Phosphoproteins / genetics* Promoter Regions, Genetic / genetics Protein Biosynthesis RNA, Messenger / genetics RNA, Messenger / metabolism Recombinant Fusion Proteins / genetics Recombinant Fusion Proteins / metabolism Ribosomes / metabolism* Sequence Deletion Smad5 Protein Trans-Activators / genetics* Transcription, Genetic Xenopus
IF 11.147
Times Cited 25
Human and Animal Cells