MATILDA

The stability and translational activity of messenger RNAs (mRNAs) are important checkpoints in the regulation of gene expression. These processes are massively reprogrammed during development and in response to stress. In the last couple of years, several studies have shown that stability and translation of mRNAs are intertwined through a mRNA degradation pathway, called 5'-3’ co-translational decay (CoTD). Our knowledge of this interconnection is still limited with the actors, mechanisms and functions remain to be discovered. The objective of the MATILDA project is to understand the role and physiological importance of this degradation pathway in the plant model Arabidopsis thaliana. We have already demonstrated the importance of this degradation pathway during development and in response to heat stress. However, the importance of this pathway in the general mechanism of mRNA decay has never been assessed in any model organism. For this project, we have set up a transgenic line allowing the discrimination between the co-translational degradation pathway and the classical cytosolic degradation pathway. In the project, we will determine the general stability of transcripts using an in vivo RNA labeling approach using this transgenic line in order to determine the importance of co-translational decay in the general mRNA stability (WP1). We will then determine the cis-elements triggering this pathway. Our preliminary data suggest the importance of codon optimality in the regulation of this mechanism (WP2). We will try to identify the signaling pathway that modulates the co-translational decay activity within the plant (WP3). Finally, we will determine the physiological conditions where the co-translational decay plays an important role (WP4). In conclusion, the MATILDA project will produce crucial knowledge on the function of the co-translational decay in plants and more generally on the role of post-transcriptional regulation of mRNAs in development and stress response in eukaryotes.