Inhibition of translation in living eukaryotic cells by an RNA G-quadruplex motif.
Guanine-rich sequences can adopt intramolecular four-stranded structures, called G-quadruplexes. These motifs have been intensively investigated on the DNA level, but their overall biological relevance remains elusive. Only recently has research concerning the function of G-quadruplexes in RNAs commenced. Here, we demonstrate for the first time, that an RNA G-quadruplex structure inhibits translation in vivo in eukaryotic cells. We investigated the function of a highly conserved, thermodynamically stable RNA G-quadruplex in the 5'-UTR of the mRNA of the human Zic-1 zinc-finger protein. Using dual luciferase reporter assay, we demonstrate that the Zic-1 RNA G-quadruplex represses protein synthesis inside eukaryotic cells. Quantitative RT-PCR assays confirmed that the reduction of protein synthesis is due to regulation of the translation process and not a consequence of reduced transcription. Western blot analysis revealed that expression of Zic-1 is strongly reduced by a 73 nucleotides-long fragment of the UTR containing the G-quadruplex motif. These structures might add to the more recently discovered elements in untranslated regions of mRNAs that regulate their translation.
Institute for Chemistry and Biochemistry, Free University of Berlin, Berlin, Germany.
Amit
A
Arora
Mariola
M
Dutkiewicz
Vinod
V
Scaria
Manoj
M
Hariharan
Souvik
S
Maiti
Jens
J
Kurreck
D020121:5' Untranslated Regions / Q000737:chemistry* / Q000378:metabolism*; D001483:Base Sequence; D015153:Blotting, Western; D005786:Gene Expression Regulation; D015894:Genome, Human; D006367:HeLa Cells; D006801:Humans; D009690:Nucleic Acid Conformation; D014176:Protein Biosynthesis; D013816:Thermodynamics; D014157:Transcription Factors / Q000235:genetics*
D020121:5' Untranslated Regions; D014157:Transcription Factors; C492123:ZIC1 protein, human