Recently Discovered RNA May Serve as Key to the Mystery of Stem Cells

Author:  Falishia Sloan
Institution:  Eastern Virginia Medical School
Date:  November 2007

In research featured recently in Nature, a group led by Dr. Haifan Lin, Director of the Yale Stem Cell Center and professor of cell biology at Yale School of Medicine, has found that newly discovered piwi-interacting RNAs (piRNAs) may have a greater genetic function, specifically in stem cells, than previously thought.

Dr. Lin, who first identified piRNAs in mammalian reproductive cells last year, and his Ph.D. student Hang Yin, have found that one type of piRNA binds to the stem cell self-renewal protein Piwi. This protein, in turn, binds to chromatin, a protein and DNA structure whose job it is to ensure efficient DNA packaging and strength and to control the expression of genes. This relationship suggests that piRNA might have a role in the regulation of genetic activity, and stem cell behavior and other processes of tissue development, as well.

Dr. Lin said, "This is important in maintaining self-renewal of stem cells. These small RNAs might provide new tools to harness the behavior of stem cells and other biological processes related to diseases."

Parts of the genome that seemingly have no obvious function have been dubbed "junk DNA" by molecular biologists. This vast area of "junk DNA" is actually non-coding DNA, which accordingly does not code for proteins as does coding DNA. Some scientists are not convinced that "junk" DNA is really useless. This current research by Dr. Lin and his Ph.D. student concerning piRNA, which is derived mostly from "junk" DNA, suggests that there may be more to the function of this untapped region of the genome.

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

Written by Falishia Sloan

Reviewed by Emma Wear

Published by Pooja Ghatalia.