Recent discoveries in the field of epigenetics continue to transform the “light switch” examples of gene regulation with which the 30+ crowd was schooled into something a little more complicated…like an airplane cockpit. We’re not talking your average Cessna either, more like an Airbus A380.
Evidence from a number of miRNA studies have added them to the expanding panel of regulatory controls, with many researchers suggesting that these inhibitors act as fine-tuning dials that adjust the mean expression level of their target genes. But could miRNAs really make their way into our transcriptome as fine-tuners?
In a perspective appearing in Genome Research this week , Dr. Chung-I Wu and colleagues call attention to another miRNA function that you hear much less about, expression buffering, that might shed some light on paradoxical miRNA data and provide insights into miRNA function in evolution.
Dialing in miRNA Function in Evolution
Unlike their proposed role as fine-tuners, miRNAs as expression buffers don’t adjust the mean expression of their targets, but rather put a choke hold on the expression variance their target genes often exhibit in response to various environmental inputs.
The researchers explain how the gene expression buffering function could be a more likely explanation for the emergence and persistence of miRNAs throughout evolution since they act to stabilize the entire transcriptome, rather than tweaking mean gene expression here and there.
The concept of miRNAs as variance busters that provide a selective advantage isn’t really an ultimatum though. Wu points out that miRNAs may have been initially selected for because of their transcriptome stabilizing prowess, but once integrated into the transcriptome, were free to explore other job functions, like gene expression fine-tuning. It’s more of a prequel than an alternative ending. Either way you’ll want to check it out at: Genome Research, May 2009