N-adenosine (mA) mRNA methylation is required for Tribolium castaneum development and reproduction.

Gene expression is regulated at various levels, including post-transcriptional mRNA modifications, where mA methylation is the most common modification of mRNA. The mA methylation regulates multiple stages of mRNA processing, including splicing, export, decay, and translation. How mA modification is involved in insect development is not well known. We used the red flour beetle, Tribolium castaneum, as a model insect to identify the role of mA modification in insect development. RNA interference (RNAi)-mediated knockdown of genes coding for mA writers (mA methyltransferase complex, depositing mA to mRNA) and readers (YTH-domain proteins, recognizing and executing the function of mA) was conducted. Knockdown of most writers during the larval stage caused a failure of ecdysis during eclosion. The loss of mA machinery sterilized both females and males by interfering with the functioning of reproductive systems. Females treated with dsMettl3, the main mA methyltransferase, laid significantly fewer and reduced-size eggs than the control insects. In addition, the embryonic development in eggs laid by dsMettl3 injected females was terminated in the early stages. Knockdown studies also showed that the cytosol mA reader, YTHDF, is likely responsible for executing the function of mA modifications during insect development. These data suggest that mA modifications are critical for T. castaneum development and reproduction.