Here’s a fun fact about your DNA: only 2% of it contains actual genes!
The rest of the 98%, often called “junk DNA,” was long thought to do nothing essential.
But scientists now know that much of this DNA contains special sections called enhancers. They’re like switches that turn genes on and off, and they can play a key role in the way our cells work.
Now researchers at UNSW Sydney have discovered a group of these switches that help control how brain cells called astrocytes work.
Astrocytes are support cells in the brain that help neurons and are linked to diseases such as Alzheimer’s disease.
Research published in the journal Nature Neuroscience states that a team studied nearly 1,000 of these DNA switches, or enhancers, in human astrocytes grown in a laboratory.
They used a powerful tool called CRISPRi, which can knock out small pieces of DNA without cutting them, and combined this with single-cell RNA sequencing, a method that measures gene activity in each cell. This helped them figure out which switches actually control important genes.
The lead author, Dr. Nicole Green, explained that when they turned off some of these enhancers, they saw a difference in the way genes behaved. This is how they knew that they had found real, working gene switches.
Of the 1,000 units tested, approximately 150 were found to be functional. Many of these were found to control genes involved in Alzheimer’s disease.
These 150 amplifiers give scientists a much smaller and more focused number of places to look as they try to understand the genetics behind Alzheimer’s disease.
Professor Irina Voineagu, who led the project, said the findings are useful not only for Alzheimer’s disease, but also for other diseases.
When scientists look for the genetic causes of diseases such as diabetes, heart disease or mental disorders, the changes they find in the DNA often occur in those ‘intermediate’ parts, and not directly in the genes. The new list of real enhancers in brain cells may help explain what those DNA changes actually do.
Another exciting possibility is the use of this research in future treatments. Because different enhancers work in different cell types, it may one day be possible to control only genes in certain brain cells, such as astrocytes, without affecting others, leading to precise therapies.
