Translational regulation of the JunD messenger RNA

John D. Short, Curt M. Pfarr

Research output: Contribution to journalArticlepeer-review

44 Scopus citations

Abstract

JunD, a member of the Jun family of nuclear transcription proteins, dimerizes with Fos family members or other Jun proteins (c-Jun or JunB) to form the activator protein 1 (AP-1) transcription factor. The junD gene contains no introns and generates a single mRNA. Here we show that two predominant JunD isoforms are generated by alternative initiation of translation, a 39-kDa full-length JunD protein (JunD-FL) by initiation at the first AUG codon downstream of the mRNA 5′ cap and a shorter, 34-kDa JunD protein (AJunD) by initiation at a second in-frame AUG codon. The JunD mRNA contains a long, G/C-rich 5′-untranslated region that is predicted to be highly structured and is important for regulating the ratio of JunD-FL and AJunD protein expression. A third functional out-of-frame AUG directs translation from a short open reading frame positioned between the JunD-FL and ΔJunD start sites. In addition, three non-AUG codons also support translation, an ACG codon (in-frame with JunD) and a CUG are positioned in the 5′-untranslated region, and a CUG codon (also in-frame with JunD) is located downstream of the short open reading frame. Mutation of these start sites individually had no affect on ΔJunD protein levels, but mutation of multiple upstream start sites led to an increase in ΔJunD protein levels, indicating that these codons can function cumulatively to suppress ΔJunD translation. Finally, we show that the JunD mRNA does not possess an internal ribosome entry site and is translated in a cap-dependent manner.

Original languageEnglish (US)
Pages (from-to)32697-32705
Number of pages9
JournalJournal of Biological Chemistry
Volume277
Issue number36
DOIs
StatePublished - Sep 6 2002

ASJC Scopus subject areas

  • Biochemistry
  • Molecular Biology
  • Cell Biology

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