Suppression of transposon mobilization by m6A-mediated RNA sequestration in stress granules

Abstract

Transposon is a mobile and ubiquitous DNA that can vastly causes genomic alterations. In plants, it is well documented that transposon mobilization is strongly repressed by DNA methylation; however, the roles of RNA methylation in transposon control remain unknown. Here we suggest that transposon RNA is marked by m6A RNA methylation and is sequestered in stress granule (SG) in m6A-dependent manner. Intriguingly, a SG-localized AtALKBH9B selectively demethylates a heat-activated retroelement Onsen, and thereby releases from spatial confinement allowing for its mobilization. In addition, we show evidence that m6A RNA methylation contributes to transpositional suppression by inhibiting the virus-like particles assembly and extrachromosomal DNA production. In summary, this study unveils a hidden role for m6A in the suppression of transposon mobility and provides an insight into how transposon counteracts the hosts epitranscriptomic control by hitchhiking RNA demethylase.