TTAGGG, TTAGGG, TTAGGG, TTAGGG. That's the piece of the genetic code repeated thousands of times in telomeres, the protective caps on the ends of chromosomes. Now, two groups of scientists have independently discovered that human cells transcribe this seemingly meaningless pattern into RNA molecules, a finding that could have implications for understanding cancer and aging.
Scientists have thought that telomeres merely protect chromosome ends from fraying and other damage, much like the plastic tips on shoelaces. Often, transcribing the genetic information encoded in DNA into matching RNA molecules is the first step in making a protein based on the gene. There seemed to be little reason for cells to transcribe the repetitive DNA in telomeres.