Targeted manipulation of m⁶A RNA modification through CRISPR-Cas-based strategies

N⁶-methyladenosine (m⁶A) is a reversible and prevalent internal modification in RNAs and can be dynamically modulated by methyltransferase and demethylase. Targeted manipulation of m⁶A RNA modification is critical in studying the functions of specific m⁶A sites as well as developing molecular therapies through targeting m⁶A. The CRISPR-Cas systems including CRISPR-Cas9 and CRISPR-Cas13 have been widely used to edit and modify specific nucleotides on DNA and RNA through fusing effective proteins such as enzymes with Cas9/13. Through taking advantage of the m⁶A methyltransferase and demethylase, a series of CRISPR-Cas-based methods have also been developed to manipulate the m⁶A methylation at specific RNA sites. This review summarizes the latest CRISPR-Cas13 and Cas9 toolkits for m⁶A site-specific manipulation, including fundamental components, on-target efficiency, editing window, PAM/PFS requirement, and subcellularly localized targeting as well as potential limitations. We thus aim to provide an overview to assist researchers to choose an optimal tool to manipulate m⁶A for different purposes and also point out possible optimization strategies.