10 years ago, when researchers began to analyze a structure called CRISPR in bacteria and archaea, they didn't expect it to bring a storm to the world of gene editing. In the past year and a half, CRISPR method quickly swept the whole animal kingdom and became an "instant" technology for DNA mutation and editing-so far it can work in almost all experimental cell types, including human cells, mice, zebrafish and Drosophila cells; This technology is also easy to operate. Two research teams have used CRISPR to analyze almost every single mutation in human cells (detailed report Science: CRISPR/CAS9 accelerates gene mining; Science: Zhang Feng established CRISPR/Cas9 human cell knockout system). Just recently, CRISPR also helped researchers to complete an engineering monkey with special gene damage, a feat that has been achieved in mice before, but not in primates (cell details: China scientists used CRISPR/Cas9 technology to construct a genetically engineered monkey).
CRISPR itself is a defense system, which can protect bacteria and archaea cells from viruses. CRISPR sites in the genomes of these organisms can express small molecular RNA that matches the genome sequence of the invading virus. When a microorganism infects one of the viruses, CRISPR RNA can combine with the virus genome through complementary sequences, and express the enzyme related to CRISPR, namely Cas. These enzymes are nucleases, which can cut viral DNA and prevent viruses from completing their functions.
The application of CRISPR/Cas system to other non-bacterial cells needs to meet two conditions: one is to cut off the target DNA, such as the DNA fragment in the target gene, and the other is an RNA molecule called Targeted RNA (gRNA), which can combine with the target through complementary action. GRNA is a short version of CRISPR RNA in bacterial cells, which can form a complex with Cas and guide Cas to the correct shearing site. However, researchers can also adjust the role of this tool in gene correction and gene regulation by combining other components or changing the activity of Cas.