From the Immune Response to the Genome Design; CRISPR-Cas9 System: Review [Bağışıklık Yanıtından Genom Tasarımına; CRISPR-Cas9 Sistemi]

The CRISPR (clustered regularly interspaced short palindromic repeat)/Cas9 (CRISPR -associated nuclease-9) system is a versatile tool for genome engineering that uses a guide RNA (gRNA) to target Cas9 to a specific genomic region. In recent years, this RNA-guided genome-editing technology has become a revolutionary tool in molecular biology and has many innovative applications in different fields. CRISPR/Cas system is not found in eukaryotic genomes, whereas a powerful defence strategy against viral invaders in the genomes of prokaryotic organisms. Native CRISPR/Cas systems have a variety of enzymes responsible for degradation of foreign DNA as well as the RNA guides required for endonuclease function, however when used for genome editing in eukaryotes, the only CRISPR protein required is the Cas9 endonuclease or a variant thereof. Using CRISPR system as a tool for altering genomes is due to the ability of Cas9 protein to cause doublestranded breaks in DNA after binding with short guide RNA molecules. CRISPR technology is candidate to solve several complex molecular biology problems faced in life science research including cancer research. In this review, CRISPR-Cas will be handled as an immune system regulator and immune system response steps will be defined in prokaryotic organisms. Repair mechanisms of DNA strand breaks and guide RNAs will be defined in means of using CRISPR-Cas9 system in genome editing and efficient transfection methods minimalized for off target effects will be discussed. Finally, CRISPR applications in cancer and therapeutic efficiency of genome editing technology will be evaluated. © 2017 by Türkiye Klinikleri.