The CRISPR-Cas9 gene editing system that has revolutionized genetic engineering in the last decade involves cutting DNA strands, which is a process that can be quite difficult to control and can lead to unwanted genetic changes. Now, thanks to researchers at the Massachusetts Institute of Technology and the University of California, San Francisco (UCSF), a new gene editing technology called CRISPRoff may change that, according to a press release.
The technique, described in a paper published in Cell on April 9, is reversible unlike the traditional CRISPY, and the changes introduced can even be transmitted to future cell lines. This non-destructive gene editing protein acts as a simple gene switch, recreating the benefits of the widely used CRISPR-Cas9 system without damaging the genetic material of cells.
“It simply came to our notice then [from the initial grant], and CRISPRoff ultimately works as predicted in a science-fiction way, “says co-senior author Luke Gilbert.” It’s exciting to see it work so well in practice. “
“The big story here is that we now have a simple tool that can silence the vast majority of genes,” says Jonathan Weissman, who is also a biology professor at MIT and an investigator at the Howard Hughes Medical Institute. We can do this for multiple genes at the same time, without any DNA damage, with great homogeneity, and in a way that can be reversed. It is an excellent tool for controlling gene expression.
“Genetic Engineering 2.0”
In the classic CRISPR-Cas9 system, it is difficult to limit the result, which is where researchers saw an opportunity for another type of gene editor.
The researchers created a small protein machine to build an epigenetic editor that could mimic the natural methylation of DNA, which is an epigenetic mechanism that occurs by adding a methyl group (CH3) to DNA. The machine, guided by small RNAs, can transform methyl groups into specific points on the strand. The methylated lashes are then “silenced” or stopped, hence the name of the car.
This does not alter the sequence of the DNA strand, allowing researchers to reverse the noise-reducing effect using enzymes that remove methyl groups. The researchers called this method CRISPRon.
The researchers found that they could use this on-off switch to target most genes in the human genome. Moreover, it worked for the genes themselves, as well as for the other regions of DNA that control gene expression without encoding proteins.
In addition, large methylated regions called CpG islands, something that was thought to be necessary for the mechanism of DNA methylation, were also silenced by CRISPRoff.
CRISPRoff for practical applications
The method was tested on induced pluripotent stem cells, which are cells that can transform into other cell types in the body. When the researchers silenced a gene in stem cells and induced them to turn into neurons, the gene was found to remain silent in 90 percent of the cells. This reveals that the cells retain a memory of the epigenetic changes made by the CRISPRoff system.
In another study, researchers used the technology to silence the Tau protein, which can form clumps in the brain that cause memory loss and are involved in Alzheimer’s disease in neurons. It has been seen that, although not completely stopped, CRISPRoff could be used to reject Tau’s expression. “What I’ve shown is that this is a viable strategy for silencing you and preventing the expression of that protein,” says Weissman. “The question is, then, how do you offer this to an adult? And would it really be enough to have an impact on Alzheimer’s? These are big open questions, especially the last ones. “
Researchers are now looking for new ways to apply gene editing technology. “With this new CRISPRoff technology, you can [express a protein briefly] to write a program that is remembered and carried out endlessly by the cell, “says Gilbert.” Change the game, so now you are practically writing a change that is transmitted through cell divisions – in some ways, we can learn to create a version 2.0 of CRISPR-Cas9, which is safer and just as effective and can do all this other things. “