The research is published in the journal Developmental Cell.
This work focuses on the formation of somites, which are tissue segments in the mesoderm of embryos that give rise to the ribs, vertebrae and muscle in all vertebrates, including humans.
Within the segmentation clock, genes are turned on and make RNA, and resulting proteins then turn off the genes, and so on, and the pattern repeats until all necessary somites are formed. Experts in tissue segmentation liken the oscillating cycle of gene activation and de-activation that cells go through before they form somites to the wave that fans perform in a stadium.
The downward part of the cycle when the wave fans are seated is just as critical as the upward cycle, when fans are standing. This means the RNA that genes make on their way up must be destroyed so the genes can be turned off. Existing mathematical models of the segmentation clock suggest that the half-life of RNA is tightly controlled, but can't say how.
"We were interested in identifying the mechanisms that made this RNA unstable enough that it would make these perpetual oscillations," Cole said. A graduate student in her lab pointed the way to microRNAs, which can destabilize their target transcripts segments of RNA produced early in the gene expression process.
"MicroRNAs can either stop protein from being made or target an RNA to be destroyed. That's what we think is happening here: It's targeting RNA to be destroyed," said Cole, also an investigator in Ohio State's Comprehensive Cancer Center.
The microRNA identified in the study is known as mir-125a-5p. While microRNAs used to be considered useless parts of the genome, they are now recognized for their power in influencing protein production even though the
|Contact: Susan Cole|
Ohio State University