Despite progress in decoding the genome, scientists estimate that fully 95 percent of our DNA represents dark, unknown territory. In the October 1 issue of the journal Cell researchers at The Wistar Institute shed new light on the genetic unknown with the discovery of the ability of long non-coding RNA (ncRNA) to promote gene expression. The researchers believe these long ncRNA molecules may represent so-called gene enhancer elementsshort regions of DNA that can increase gene transcription. While scientists have known about gene enhancers for decades, there has been no consensus about how these enhancers work.
These findings join a growing body of evidence that the classic "central dogma" of genetics is incomplete. In the central dogma, chromosomal DNA is transcribed into RNA, which is then translated by the cell into proteins. In recent years, however, scientists have found that not all transcribed RNA molecules become translated into proteins. In fact, studies have shown that whole swathes of the genome are transcribed for unknown reasons.
In the present study, the Wistar researchers pinpoint 3,000 long ncRNAs and estimate that there could be a total of between 10,000 to 12,000 long ncRNA sequences within our DNA. This number is comparable to the 20,000 genes that are known to encode proteins. Most long ncRNAs are encoded in DNA near genes known to be important to both stem cells and cancer. This observation also suggests that targeting ncRNAs may represent a new strategy in slowing cancer growth.
"We are excited, first of all, because this is a new discovery about the very nature of human DNA; a new class of genetic object and a new layer of genetic regulation," said Ramin Shiekhattar, Ph.D., Wistar's Herbert Kean, M.D., Family Professor and senior author of the study.
"Secondly, we may have solved, in part, a great mystery in modern genetics. These long non-coding RNA sequences may account for the activity of enhan
|Contact: Greg Lester|
The Wistar Institute