Comparative analysis of the structural and expressional parameters of microRNA target genes

MicroRNAs (miRNAs) generally pair with the 3′UTRs of their target mRNAs to repress gene expression. It has reported that miRNA targets (TGs) are longer and evolve more slowly than non-targets (NTGs). We confirmed the observation and also found novel structural and expressional characteristics of TGs. The length difference between TGs and NTGs was greatest for the 3′UTRs, although a difference was also observed for CDSs and introns. Widely expressed genes were shorter for both TGs and NTGs; however, TGs were significantly longer than NTGs in all ranges of expression. TGs were more likely than NTGs to be widely expressed, which might explain why TGs evolve more slowly than NTGs. Finally, we found that TG mRNAs have faster decay rates. In addition, the decay rate of a TG mRNA transcript was found to be positively correlated with the number or density of target sites located in that TG's mRNA transcript.

► The size difference between TGs and NTGs is greatest for the 3′UTRs.
► TGs are significantly longer than NTGs in all ranges of expression.
► TGs are more likely than NTGs to be widely expressed.
► TG mRNAs have faster decay rates.
► The decay rate of a TG mRNA is positively correlated with the number or density of target sites.