DXO1 involves in ABA regulation through m7G capping

While m7G capping was once considered a constitutive housekeeping process, emerging evidence suggests that it is dynamically regulated to influence gene expression in response to stimuli, although the underlying mechanisms remain largely unknown. The recent discovery of NAD-capped RNAs (NAD-RNAs) adds complexity to the role of RNA capping in gene regulation.

Arabidopsis DXO1 has been identified as a decapping enzyme for NAD-RNAs (deNADding), and its loss-of-function mutation has been reported to cause pleiotropic phenotypes, including reduced sensitivity to ABA. Recently, we found that DXO1 is also a crucial component of m7G capping, acting as an activator of RNMT1, which methylates the unmethylated guanosine cap of mRNA to produce the m7G cap. In this study, we demonstrate that DXO1 contributes to the ABA response not through its role as a deNADding enzyme, but rather through its function in m7G capping.