Big role for tiny RNA

Tiny RNAs discovered in “junk” DNA play an important role in controlling gene function, Yale scientists reported in the journal Nature in October.

A team led by Haifan Lin, Ph.D., director of the Yale Stem Cell Center and professor of cell biology, discovered these RNAs, called piRNAs, in mammalian reproductive cells in 2006. The team’s findings suggest that piRNAs also exist in nonreproductive body cells and help to control stem cell fate and tissue development. The researchers found that a particular piRNA forms a complex with a protein called Piwi, which then binds to a specific region of chromatin (i.e., the genome) that regulates gene activity.

“This finding revealed a surprisingly important role for piRNAs, as well as junk DNA, in stem cell division,” Lin said. “It calls upon biologists to look for answers beyond the 1 percent of the genome with protein-coding capacity to the vast land of junk DNA, which constitutes 99 percent of the genome.”