A Unified Model for the Function of YTHDF Proteins in Regulating m<sup>6</sup>A-Modified mRNA.

Overview

N⁶-methyladenosine (m⁶A) is the most abundant mRNA nucleotide modification and regulates critical aspects of cellular physiology and differentiation. m⁶A is thought to mediate its effects through a complex network of interactions between different m⁶A sites and three functionally distinct cytoplasmic YTHDF m⁶A-binding proteins (DF1, DF2, and DF3). In contrast to the prevailing model, we show that DF proteins bind the same m⁶A-modified mRNAs rather than different mRNAs. Furthermore, we find that DF proteins do not induce translation in HeLa cells. Instead, the DF paralogs act redundantly to mediate mRNA degradation and cellular differentiation. The ability of DF proteins to regulate stability and differentiation becomes evident only when all three DF paralogs are depleted simultaneously. Our study reveals a unified model of m⁶A function in which all m⁶A-modified mRNAs are subjected to the combined action of YTHDF proteins in proportion to the number of m⁶A sites.