Scientists have taken a step closer to editing RNA, which could be the next step of CRISPR – TechCrunch

Researchers at the prestigious Salk Institute reports that they have successfully mapped the molecular structure of a CRISPR enzyme that could allow scientists to more precisely manipulate the functions within cells.

In recent years, CRISPR-Cas9 has captured the public's imagination for its ability to alter the genetic code to correct defects within individual cells – potentially healing mutations and preventing onset many diseases.

Specifically, Cas9 enzymes act like scissors, cutting pieces of genetic code and replacing them with a replacement. But these enzymes target DNA, which is the cornerstone of the development of an organism, and there is growing fear that the use of the enzyme to reprogram essentially the DNA of a cell can cause more harm than good.

As the report illustrates in Scientific American:

A study published Monday suggests that it is only the tip of the iceberg of the size of the Titanic: the CRISPR-Cas9 study can cause significantly greater genetic havoc than was thought by the experts, may be enough to threaten the health of patients.

The results were difficult following two studies that found a related problem: some CRISPR'd cells may miss a key anti-cancer mechanism and thus be able to initiate tumors.

Complex for editing CRISPR-CAS9 genes of Streptococcus pyogenes. The Cas9 nuclease protein uses a guide RNA sequence to cut DNA at a complementary site. Protein Cas9: white surface model. DNA fragments: caricature in blue scale. ARN: caricature in red scale. Photo courtesy Getty Images

The Salk Institute's new findings, published in the journal Cell, provide the detailed molecular structure of CRISPR-Cas13d, an enzyme capable of targeting RNA rather than DNA.

Once thought to be simply the mechanism for issuing instructions encoded in DNA for cellular operations, RNA is now known to perform biochemical reactions such as enzymes and serve their own regulatory functions in cells. By identifying an enzyme that can target the mechanisms by which cells function, rather than the overall plan of cellular function, scientists should be able to offer even more sophisticated treatments with less risk.

Simply put, having editing tools can allow scientists to alter the activity of a gene without permanently altering – and potentially dangerous – the gene itself seems to be a good option to explore.

"The DNA is constant, but what constantly changes are the RNA messages that are copied from the DNA," says Salk Silvana Konermann, research associate, Hanna Gray Fellow, member of the Howard Hughes Medical Institute and one of the first authors of the study, in a statement. "Being able to modulate these messages by directly controlling RNA has important implications for influencing the fate of a cell."

Salk researchers first identified the family of enzymes they call CRISPR-Cas13d earlier this year and suggested that this alternative system could recognize and cut RNA. Their first work was on the treatment of dementia and the team showed that the tool could be used to correct protein imbalances in the cells of patients with dementia.

"In our previous article, we discovered a new CRISPR family that can be used to create RNA directly inside human cells," Helmsley said.Salk Patrick Hsu, the other corresponding author of the new work. "Now that we've been able to visualize the structure of Cas13d, we can see in more detail how the enzyme is guided to RNA and how it is able to cut RNA. This information allows us to improve the system and make the process more efficient, paving the way for new strategies to treat RNA diseases. "

The other authors of the journal were Nicholas J. Brideau and Peter Lotfy of Salk; Xuebing Wu of the Whitehead Institute for Biomedical Research; and Scott J. Novick, Timothy Strutzenberg and Patrick R. Griffin of the Scripps Research Institute, according to a statement.