Open AccessThe 5'-untranslated region of the mouse mammary tumor virus mRNA exhibits cap-independent translation initiation
Author(s) -
Maricarmen Vallejos,
Pablo Ramdohr,
Fernando Valiente-Echeverría,
Karla Tapia,
Felipe Rodriguez-Tirado,
Fernando Lowy,
J. Pablo HuidobroToro,
John A. Dangerfield,
Marcelo López-Lastra
Publication year - 2009
Publication title -
nucleic acids research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 9.008
H-Index - 537
eISSN - 1362-4954
pISSN - 0305-1048
DOI - 10.1093/nar/gkp890
Subject(s) - biology , internal ribosome entry site , luciferase , microbiology and biotechnology , untranslated region , polyadenylation , five prime untranslated region , messenger rna , three prime untranslated region , cistron , translation (biology) , transfection , virology , gene , rna , genetics
In this study, we demonstrate the identification of an internal ribosome entry site (IRES) within the 5'-untranslated region (5'-UTR) of the mouse mammary tumor virus (MMTV). The 5'-UTR of the full-length mRNA derived from the infectious, complete MMTV genome was cloned into a dual luciferase reporter construct containing an upstream Renilla luciferase gene (RLuc) and a downstream firefly luciferase gene (FLuc). In rabbit reticulocyte lysate, the MMTV 5'-UTR was capable of driving translation of the second cistron. In vitro translational activity from the MMTV 5'-UTR was resistant to the addition of m(7)GpppG cap-analog and cleavage of eIF4G by foot-and-mouth disease virus (FMDV) L-protease. IRES activity was also demonstrated in the Xenopus laevis oocyte by micro-injection of capped and polyadenylated bicistronic RNAs harboring the MMTV-5'-UTR. Finally, transfection assays showed that the MMTV-IRES exhibits cell type-dependent translational activity, suggesting a requirement for as yet unidentified cellular factors for its optimal function.