A CONTROVERSIAL theory could help explain growing evidence that many genes do more than code for proteins.
At the simplest level, part of one of the two strands of DNA 鈥� the 鈥渟ense鈥� strand 鈥� is copied to create a single-stranded RNA that acts as a template for making a protein. But it is becoming clear that animals produce far more RNA than needed to make proteins.
The main reason for this, according to Tom Gingeras of the Californian DNA chip company Affymetrix, is that many genes also churn out something called 鈥渁ntisense鈥� RNA. Antisense RNA, made from the other, complementary DNA strand, can bind to the sense RNA and block protein production. Gingeras thinks that antisense RNA plays a key role in regulating gene activity, and that it is made in response to environmental or developmental cues.
Advertisement
While antisense RNA is already thought to regulate the activity of a few key genes, Gingeras is suggesting that this is widespread. He came up with his ideas after searching human chromosomes 21 and 22 for the points where RNA production starts. His team鈥檚 results suggest that most of the 800 or so genes on these chromosomes produce both sense and antisense RNA. 鈥淲e believe it鈥檚 a general strategy, that a large proportion of genes have an antisense gene,鈥� Gingeras told the Lorne meeting. 鈥淭here鈥檚 going to be a very heated debate.鈥�
Others think more evidence is needed. 鈥淭he question is whether the antisense transcript actually has a function 鈥� whether it is the consequence or cause of normal gene control,鈥� says David Hume of the University of Queensland in Brisbane, part of a team that discovered that many genes in mice also produce antisense RNA. But he thinks one thing is clear: we should stop thinking of genes merely as recipes for proteins.
