Utilization of crispr in gene function and drug target validation

Clustered regularly interspaced short palindromic repeat (CRISPR) is a useful tool in functional genome studies and drug target validation. Compared with RNA interference (RNAi) technology, CRISPR-based screening approach implements two-direction regulation of gene, targeting both coding and non-coding regions of the genomes of human and other model organisms both in vitro and in vivo. CRISPR can function in a transient or a constitutive mode. The feasibility of single guide RNA (sgRNA) design and synthesis provides the technology comparable throughput with RNAi and renders wider application than previous generations of gene editing technologies. Current studies use three types of CRISPR systems: the wildtype Cas9 protein, the paired Cas9 nickases and the CRISPR interfering/activating scaffold. The improvement aims of this technology include, but are not limited to, the specificity, on-target efficiency, throughput and data deconvolution. This chapter introduced some cases of CRISPR applications in diverse fields, such as mechanistic toxicology, disease model construction, drug target and drug resistance-associated gene identification.