The 5'-untranslated region of GM-CSF mRNA suppresses translational repression mediated by the 3' adenosine-uridine-rich element and the poly(A) tail

Jason A. Jarzembowski, Lakshman E. Rajagopalan, Hyun C. Shin, James S. Malter

Research output: Contribution to journalArticle

12 Scopus citations

Abstract

Granulocyte-macrophage colony stimulating factor (GM-CSF) mRNA levels are controlled post-transcriptionally by the 3'-untranslated region (UTR) adenosine-uridine-rich element (ARE). In untransformed, resting cells, the ARE targets GM-CSF mRNA for rapid degradation, thereby significantly suppressing protein expression. We used a rabbit reticulocyte lysate (RRL) cell-free system to examine translational regulation of GM-CSF expression. We uncoupled decay rates from rates of translation by programming the RRL with an excess of mRNAs. Capped, full-length, polyadenylated human GM-CSF mRNA (full-length 5'-UTR AUUUA+A90) and an ARE-modified version (full-length 5'-UTR AUGUA+A90) produced identical amounts of protein. When the 5'-UTR was replaced with an irrelevant synthetic leader sequence (syn 5'-UTR), translation of syn 5'-UTR AUUUA+A90 mRNA was suppressed by > 20-fold. Mutation of the ARE or removal of the poly(A) tail relieved this inhibition. Thus, in the absence of a native 5'-UTR, the ARE and poly(A) tail act in concert to block GM-CSF mRNA translation. Substitutions of different regions of the native 5'-UTR revealed that the entire sequence was essential in maintaining the highest rates of translation. However, shorter 10-12 nt contiguous 5'-UTR regions supported 50-60% of maximum translation. The 5'-UTR is highly conserved, suggesting similar regulation in multiple species and in these studies was the dominant element regulating GM-CSF mRNA translation, overriding the inhibitory effects of the ARE and the poly(A) tail.

Original languageEnglish (US)
Pages (from-to)3660-3666
Number of pages7
JournalNucleic acids research
Volume27
Issue number18
DOIs
StatePublished - Sep 15 1999

ASJC Scopus subject areas

  • Genetics

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