title: Minor contribution of an internal ribosome entry site in the 5'-UTR of ornithine decarboxylase mRNA on its translation.
abstract: The mechanism of synthesis of ornithine decarboxylase (ODC) at the level of translation was studied using cell culture and cell-free systems. Synthesis of firefly luciferase (Fluc) from the second open reading frame (ORF) in a bicistronic construct transfected into FM3A and HeLa cells was enhanced by the presence of the 5'-untranslated region (5'-UTR) of ODC mRNA between the two ORFs. However, cotransfection of the gene encoding 2A protease inhibited the synthesis of Fluc. Synthesis of Fluc from the second cistron in the bicistronic mRNA in a cell-free system was not affected significantly by the 5'-UTR of ODC mRNA. Synthesis of ODC from ODC mRNA in a cell-free system was inhibited by 2A protease and cap analogue (m7GpppG). Rapamycin inhibited ODC synthesis by 40-50% at both the G1/S boundary and the G2/M phase. These results indicate that an IRES in the 5'-UTR of ODC mRNA does not function effectively.
authors.affiliation: Graduate School of Pharmaceutical Sciences, Chiba University, 1-8-1 Inohana, Chuo-ku, Chiba 260-8675, Japan.
authors.forename: Kazuhiro
authors.initials: K
authors.lastname: Nishimura
authors.forename: Ai
authors.initials: A
authors.lastname: Sakuma
authors.forename: Tomoko
authors.initials: T
authors.lastname: Yamashita
authors.forename: Go
authors.initials: G
authors.lastname: Hirokawa
authors.forename: Hiroaki
authors.initials: H
authors.lastname: Imataka
authors.forename: Keiko
authors.initials: K
authors.lastname: Kashiwagi
authors.forename: Kazuei
authors.initials: K
authors.lastname: Igarashi
mesh_terms: D020121:5' Untranslated Regions / Q000502:physiology*; D000818:Animals; D002455:Cell Division / Q000187:drug effects; D045744:Cell Line, Tumor; D003546:Cysteine Endopeptidases / Q000378:metabolism; D016193:G1 Phase / Q000187:drug effects; D016195:G2 Phase / Q000187:drug effects; D006367:HeLa Cells; D006801:Humans; D051379:Mice; D009955:Ornithine Decarboxylase / Q000096:biosynthesis*; D014176:Protein Biosynthesis / Q000502:physiology*; D012314:RNA Cap Analogs / Q000494:pharmacology; D012333:RNA, Messenger / Q000378:metabolism*; D011817:Rabbits; D012156:Reticulocytes / Q000378:metabolism; D012270:Ribosomes / Q000502:physiology*; D016196:S Phase / Q000187:drug effects; D020123:Sirolimus / Q000494:pharmacology; D014764:Viral Proteins / Q000378:metabolism
chemical_list: D020121:5' Untranslated Regions; D012314:RNA Cap Analogs; D012333:RNA, Messenger; D014764:Viral Proteins; D003546:Cysteine Endopeptidases; C057400:picornain 2A, Picornavirus; D009955:Ornithine Decarboxylase; D020123:Sirolimus