For about 15 years, scientists have known that certain “junk” DNA — repetitive DNA segments previously thought to have no function — could evolve into exons, which are the building blocks for protein-coding genes in higher organisms like animals and plants. Now, a University of Iowa study has found evidence that a significant number of exons created from junk DNA seem to play a role in gene regulation.
The findings, which increase understanding of how humans differ from other animals, including non-human primates, appear Oct. 17 in the open-access journal PLoS Genetics.
Nearly half of human DNA consists of repetitive DNA, including transposons, which can “transpose” or move around to different positions within the genome. A type of transposon called retrotransposons are transcribed into RNA and then reintegrated into the genomic DNA. The most common form of retrotransposons in the human genome are Alu elements, which have more than one million copies and occupy approximately 10 percent of the human genome.