Applications of the versatile CRISPR‐Cas13 RNA targeting system

Abstract CRISPR‐Cas are adaptable natural prokaryotic defense systems that act against invading viruses and plasmids. Among the six currently known major CRISPR‐Cas types, the type VI CRISPR‐Cas13 is the only one known to exclusively bind and cleave foreign RNA. Within the last couple of years, this system has been adapted to serve numerous, and sometimes not obvious, applications, including some that might be developed as effective molecular therapies. Indeed, Cas13 has been adapted to kill antibiotic‐resistant bacteria. In a cell‐free environment, Cas13 has been used in the development of highly specific, sensitive, multiplexing‐capable, and field‐adaptable detection tools. Importantly, Cas13 can be reprogrammed and applied to eukaryotes to either combat pathogenic RNA viruses or in the regulation of gene expression, facilitating the knockdown of mRNA, circular RNA, and noncoding RNA. Furthermore, Cas13 has been harnessed for in vivo RNA modifications including programmable regulation of alternative splicing, A‐to‐I and C to U editing, and m6A modifications. Finally, approaches allowing for the detection and characterization of RNA‐interacting proteins have also been demonstrated. Here, we provide a comprehensive overview of the applications utilizing CRISPR‐Cas13 that illustrate its versatility. We also discuss the most important limitations of the CRISPR‐Cas13‐based technologies, and controversies regarding them. This article is categorized under: RNA Methods > RNA Analyses in Cells RNA Processing > RNA Editing and Modification RNA Interactions with Proteins and Other Molecules > Protein‐RNA Interactions: Functional Implications