Researchers from the Massachusetts Institute of Technology (MIT) have found a new way to look for genes that protect against Parkinson’s disease. They did so by developing a modified version of the CRISPR genome-editing system.
Their work was published in the journal Molecular Cell with the title, “Randomized CRISPR-Cas Transcriptional Perturbation Screening Reveals Protective Genes against Alpha-Synuclein Toxicity.”
CRISPR enables scientists to add, delete, or alter specific parts of the genome, or DNA sequence, in living cells. It consists of two key molecules: Cas9, an enzyme that cuts the two strands of DNA at a certain location; and a small piece of RNA known as guide RNA, which is a pre-designed RNA sequence that ensures that Cas9 cuts where researchers want it to.
But in this study, the team deactivated Cas9’s cutting ability and engineered it to turn genes on. Then, they applied the modified version of CRISPR in yeast cells overproducing alpha-synuclein, a protein found in Parkinson’s disease (PD) patients’ brains.
In theory, this technique allows scientists to identify genes that protect cells from the PD-associated protein.
“What we decided to do was take a completely unbiased approach where instead of targeting individual genes of interest, we would express randomized [RNA] guides inside of the cell,” Timothy K. Lu, senior author of the study, said in a press release. “Using that approach, we can screen for guide RNAs that have unusually strong protective activities in a model of neurodegenerative disease.”
As a result, the MIT team was able to identify one guide RNA strand that kept cells alive much more effectively than any other genes that were previously found to protect this cell type. Further analysis revealed that this protective RNA guide was activating previously described protective genes.
After identifying the genes in yeast, researchers tested their human equivalents in human neurons that also produced high amounts of alpha-synuclein and found that the human genes were also protective against alpha-synuclein-induced death.
The team also noted that many of the genes turned on by this guide RNA strand coded for proteins that help other proteins fold into the correct shape. This may constitute a possible treatment for PD, as one of the known causative disease mechanisms is the formation of alpha-synuclein clumps due to incorrect protein folding. Nonetheless, further research is needed.