TRADES: Targeted RNA Demethylation by SunTag System.

N6-methyladenosine (mA) is rapidly being studied and uncovered to play a significant role in various biological processes as well as in RNA fate and functions, while the effects of defined mA sites are rarely characterized for the lack of convenient tools. To provide an applicable method to remove mA modification at specific loci, an mA editing system called "targeted RNA demethylation by SunTag system (TRADES)" is engineered. In this system, the targeting element dCas13b is fused to ten copies of GCN4 peptides which can recruit multiple scFv-fusion RNA demethylase to demethylate the target mA site. Owing to this design, TRADES is more flexible to the indistinct mA sites for its wide editing window. By site-specific demethylation of messenger RNA (mRNA) SON A2699, the lifetime of SON RNA is successfully prolonged in HeLa cells. Meanwhile, TRADES negligibly influences the lifetime of other non-targeted transcripts. TRADES also can regulate the gene expression of target transcript in an mA-dependent manner. Moreover, the interference occuring for HBV and HIV replications demonstrates that the TRADES system holds potential in viral life cycle regulation and clinical applications.