Background
Translational control is a mechanism of protein synthesis regulation emerging as an important
target for new therapeutics. Naturally occurring microRNAs and synthetic small inhibitory
RNAs (siRNAs) are the most recognized regulatory molecules acting via RNA
interference. Surprisingly, recent studies have shown that interfering RNAs may also activate
gene transcription via the newly discovered phenomenon of small RNA-induced gene
activation (RNAa). Thus far, the small activating RNAs (saRNAs) have only been demonstrated
as promoter-specific transcriptional activators.
Findings
We demonstrate that oligonucleotide-based trans-acting factors can also specifically
enhance gene expression at the level of protein translation by acting at sequence-specific
targets within the messenger RNA 5’-untranslated region (5’UTR). We designed a set of
short synthetic oligonucleotides (dGoligos), specifically targeting alternatively spliced
5’UTRs in transcripts expressed from the THRB and CDKN2A suppressor genes. The in
vitro translation efficiency of reporter constructs containing alternative TRβ1 5’UTRs was
increased by up to more than 55-fold following exposure to specific dGoligos. Moreover, we
found that the most folded 5’UTR has higher translational regulatory potential when compared
to the weakly folded TRβ1 variant. This suggests such a strategy may be especially
applied to enhance translation from relatively inactive transcripts containing long 5’UTRs of
complex structure.
Significance
This report represents the first method for gene-specific translation enhancement using
selective trans-acting factors designed to target specific 5’UTR cis-acting elements. This
simple strategy may be developed further to complement other available methods for gene
expression regulation including gene silencing. The dGoligo-mediated translation-enhancing
approach has the potential to be transferred to increase the translation efficiency of any
suitable target gene and may have future application in gene therapy strategies to enhance
expression of proteins including tumor suppressors.