Scientists Find a Crucial New Role For DNA

Monday, April 16, 2018 - 10:13

Researchers from University of Michigan have discovered that how satellite DNA, considered to be "junk DNA", plays a crucial role in holding the genome together.

Their findings, published recently in the journal eLife, indicate that this genetic "junk" performs the vital function of ensuring that chromosomes bundle correctly inside the cell's nucleus, which is necessary for cell survival. And this function appears to be conserved across many species, Science Alert reports.

This pericentromeric satellite DNA consists of a very simple, highly repetitive sequence of genetic code.

Although it accounts for a substantial portion of our genome, satellite DNA does not contain instructions for making any specific proteins.

What's more, its repetitive nature is thought to make the genome less stable and more susceptible to damage or disease.

Until fairly recently, scientists believed this so-called "junk" or "selfish" DNA did not serve any real purpose.

"But we were not quite convinced by the idea that this is just genomic junk," says Yukiko Yamashita, research professor at the University of Michigan Life Sciences Institute and lead author of the study.

The researchers removed D1 from the cells of a commonly used model organism, Drosophila melanogaster (fruit flies). And the team quickly noticed that germ cells – the cells that ultimately develop into sperm or eggs – were dying.

Further analysis revealed that the dying cells were forming micro-nuclei, or tiny buds, outside the nucleus that included pieces of the genome.

The team conducted similar experiments using mouse cells and found the same results: When they removed a protein that normally binds to mouse satellite DNA, the cells again formed micro-nuclei and did not survive.

The similar findings from both fruit fly and mouse cells lead Yamashita and her colleagues to believe that satellite DNA is essential for cellular survival, not just in model organisms, but across species that embed DNA into the nucleus – including humans.

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