Unhappy with the 60-70% gene silencing success rate of CRISPR/Cas9, researchers have come up with an innovative hack to 21st century’s biggest find, improving gene silencing frequency to a whopping 95%.
Researchers at Gladstone Institutes have shown success in turning off certain genes in induced pluripotent stem cells (iPSCs) for the very first time using a hacked CRISPR/Cas9 system. Called the CRISPRi system (since adding an “i” to anything significantly improves it). Researchers led by published their finding in Cell Stem Cell. CRISPRi showed success in silencing genes in iPSCs and heart cells created from iPSCs, with a higher success rate than just CRISPR/Cas9 system.
Unlike the CRISPR/Cas9 system where the combination is used to delete specific genes from the DNA, the CRISPRi system merely blocks this particular gene by sticking to it. This simple yet innovative hack has shown to be more effective at silencing the gene than trying to slice the gene out, where the effectivity falls to 60-70%. Cas9 is used but in its deactivated form along with a protein inhibitor called KRAB, together resulting in a more consistent performance, which could lead to reproducible results. It was shown to be more tightly bounded to the gene, akin to a software hack that only gives the intended result without the desired action.
One of the biggest flaws of the 2013 discovered CRISPR-Cas9 was its undesired insertions or deletions to the cell’s genome, however, CRISPRi did not show any off-target changes in gene expression. This offers scientists a major technological advance in creating accurate cell models of genetic diseases.
Reversing Gene Silencing and Tuning Frequency
One another feature of CRISPRi is its ability to easily reverse gene silencing by removing the protein inhibitor. One another useful feature described in the paper is the ability to tune the frequency with which the bound genes are expressed, merely by changing the amount of chemicals added.