CRISPR

CRISPR-Cas9 is a technique used for genome editing that is adapted from the bacteria’s antiviral immune response. Bacteria capture and store DNA fragments from invading viruses within a region of their genome, and these CRISPR (Clustered Regularly Interspaced Short Palindromic Repeats) guide sequences help detect and protect the bacteria from future infections. When the CRISPR guide sequences detect an invading virus or DNA whose sequence is complementary to the CRISPR guide, the Cas9 (CRISPR-associated protein 9) nuclease is recruited to specifically cleave the invading DNA, resulting in its degradation.

This CRISPR-Cas9 system has been modified for use in mammalian cells. By introducing a guide sequence (sgRNA) specific for our gene of interest, we can either knock-out specific genes through introducing frame shift mutations via Non-Homologous End Joining (NHEJ), or generate knock-in mutations through additionally providing a template for Homologous Recombination (HR).