July 19 (UPI) -- New research suggests DNA methylation and transposons can help explain the genetic origins of serious human diseases.
Transposons, DNA sequences that resemble ancient viral fragments, make up more than half of the human genome. Most of the time, these sequences are turned off. They're kept silent by a mechanism called DNA methylation.
Researchers suggest that when transposons are activated, they can trigger the development of serious human diseases.
Now, for the first time, scientists have managed to turn off DNA methylation in human stem cells.
Transposons are sometimes called jumping genes, as they can integrate themselves into DNA sequences, triggering genetic changes that can lead to harmful physiological changes. During fetal development, DNA methylation prevents transposons from interfering with normal gene expression.
"Sometimes, however, DNA methylation is disrupted and studies have shown that this is significant in certain cancer tumors and in some neuropsychiatric diseases," Johan Jakobsson, professor at Lund University in Sweden, said in a news release. "DNA methylation is used as a target for therapy in certain cancer types, such as leukemia, but we still lack knowledge about why this is effective and why it only works for certain types of cancer."
In the lab, Jakobsson and his colleagues used the gene-editing technology known as CRISPR/Cas9 to prevent DNA methylation in human stem cells. Scientists shared the results of their experiments this week in the journal Nature Communications.
"The results were very surprising. If you shut down DNA methylation in mouse cells, they don't survive," Jakobsson said. "But when DNA methylation was shut down in the human nerve stem cells, they survived and a specific set of transposons were activated. These transposons in turn affected many genes that are important in the development of the nerve cells."
In follow up studies, researchers hope to turn DNA methylation off and on in cancer cells like glioblastoma.