Yale: Genes Have Secret Sidekicks

We've all been taught in school that genes alone are responsible for our traits, but a new study carried out by Yale University researchers concluded that there is another mechanism that controls traits variations even in genetically identical individuals.

Ten years ago, scientists discovered that a striking percentage of flies lacked a protein called Hsp-90 and ended up with weird and random abnormalities (legs growing where eyes should be, for example), so they speculated that Hsp-90 protected the organism against harmful genetic variations in its genome.

But since the role of the Hsp-90 is to mobilize other molecules to respond to stress, researchers believed that there were other factors involved.

A theory said that Hsp-90 suppresses the activity of 'jumping genes' that can place themselves to different areas of the genome and cause mutations, thus preventing the display of random abnormalities.

But Yale researchers reported that, according to their work, a kind of small RNA called Piwi-interacting RNA, or piRNA, acts together with Hsp-90 and another molecule, to prevent not just the creation of variants but the activation of existing genetic variants as well.

So it's true that genes play a role in protecting against harmful variations but they work through actions of the molecules piRNA and Hsp-90.

Haifan Lin, director of the Yale Stem Cell Center, professor of cell biology and genetics and senior author of the paper presenting the research, studied piRNAs in reproductive cells and stem cells and he says that “this mechanism may help explain how ordinary cells such as fibroblasts can be converted to stem cells and why some cancers develop at random.”

The theory according to which genes are not the only ones responsible for an organism’s traits is almost 70 years old but it was not until the past decade that it started to gather adepts.

And it also explains things like cloned animals that are often born with different colors than the animals that are the source of their DNA.

“This study shows that we still have a lot to learn about the most basic principles of gene regulation,” added Lin.

“Studies of this kind may provide missing puzzles in our understanding of normal development and malignancies.”

The study was funded by the G. Harold and Leila Y. Mathers Foundation and the NIH, and the paper presenting it was published in Nature Genetics.