We all have our specialties—maybe yours is in histone modifications or maybe you can name every American Idol winner. In any case, miRNAs have some specialization too. Researchers now say that they’ve figured out what miRNAs that bind within the CDS, or coding sequence, of an mRNA do—they specialize in inhibiting translation.
Most studies talk about what happens when miRNAs bind to sites in the 3’ UTR via their seed regions—the big effect is that mRNAs get degraded, but their translation also can be hindered a bit. But no one really knows what the heck happens when miRNAs bind within the coding sequences of mRNA.
So, the Swiss-based team studied likely miRNA target sites in CDSs and compared them to target sites in the 3’ UTR. Here’s a little 411:
- Target sites in either the CDS or 3’ UTR are both under selection pressure and evolved in parallel. Their sequences and structures also are similar.
- Some miRNAs “co-target” sites in both the CDS and 3’ UTR of mRNAs. A lot of these miRNAs, when overexpressed, are linked with cancer.
- CDS-based sites are more effective at inhibiting translation (and they can do it rapidly), whereas sites in the 3’ UTR are more specialized for promoting degradation.
“Our study suggests that miRNAs may combine targeting of CDS and 3’ UTR to flexibly tune the time scale and magnitude of their post-transcriptional regulatory effects,” they say.
Want to specialize in miRNAs? Read more at Genome Research, January, 2013.