CRISPR-Cas guides the future of genetic engineering

Abstract

The diversity, modularity, and efficacy of CRISPR-Cas systems are driving a biotechnological revolution. RNA-guided Cas enzymes have been adopted as tools to manipulate the genomes of cultured cells, animals, and plants, accelerating the pace of fundamental research and enabling clinical and agricultural breakthroughs. We describe the basic mechanisms that set the CRISPR-Cas toolkit apart from other programmable gene-editing technologies, highlighting the diverse and naturally evolved systems now functionalized as biotechnologies. We discuss the rapidly evolving landscape of CRISPR-Cas applications, from gene editing to transcriptional regulation, imaging, and diagnostics. Continuing functional dissection and an expanding landscape of applications position CRISPR-Cas tools at the cutting edge of nucleic acid manipulation that is rewriting biology.

Figure 1 -. Adaptive immunity by CRISPR-Cas systems.

a) Foreign genetic elements are acquired by Cas1/Cas2 and integrated into the CRISPR-array in a process broadly termed adaptation. b) The CRISPR array and associated Cas proteins are expressed. The CRISPR array is processed and Cas effector nucleases associate with a crRNA to form an active surveillance complex. c) The Cas effector nucleases target foreign genetic elements complementary to their crRNA leading to target interference and immunity.

Figure 2 -. CRISPR-Cas systems allow genetic manipulation across the central dogma.

a) Cas9 and Cas12a are used for inducing dsDNA breaks for genome-editing. b) nCas9 can be fused to base-editors to modify nucleotides in dsDNA for genome-editing without introducing a dsDNA break. c) dCas9 can be fused to transcriptional activators, repressors, or epigenetic modifiers to regulate transcription. d) Cas9 and Cas13a can be used for targeted RNA interference. e) Cas13a fused to base-editors can be used to modify nucleotides in ssRNA. f-g) dCas9 or dCas13a can be fused to GFP to image DNA/RNA and RNA, respectively.