"What we show here is a proving ground -- a process to determine how to make the correct changes to proteins."
MicroRNA strands were once thought of as junk genetic material. Now, researchers know that these small structures help program surrounding genes, affecting everything from eye color to cancer. If DNA is like a blueprint, then RNA is the ink; it serves as the messenger between the genetic code stored in DNA and the molecules that are built following the blueprint model.
A team including Xiaoqing Tang, assistant professor of biology at Michigan Technological University, examined an array of MicroRNA -- small RNA molecules -- to try to understand how it works. Tang examined which strands were active in beta cells, which secrete insulin, and which strands were active in alpha cells, which secrete glucagon, a substance that regulates blood sugar levels
Only a few stood out, and one – miR-483 – shows a clear pattern.
[MicroRNAs] adjust gene expression levels in cells like a dimmer switch.
miR-21 has been found to increase expression of cancer-promoting genes and decreases cancer suppressors. Varani's team reasoned that, if a protein like Rbfox2 could bind to miR-21, it could repress tumor growth effects.
One challenge facing the team was that they would have to create a protein that binds bind to miR-21 and no other microRNA. The team took advantage of the fact that all RNA molecules, including microRNAs, consist of a chain of chemical nodes that "imbues them with specificity."
Phys reports that Varani's team were the first in history to manage to successfully alter a protein to bind to microRNAs.
Varani told reporters that this is because proteins have long been well-understood, but RNAs have not.
"That is because our knowledge of protein structure is much better than our knowledge of RNA structure. We historically lacked key information about how RNA folds up and how proteins bind RNA at the atomic level."
