mRNA m6A modification: biogenesis and role in mRNA stability – m6A

The control of gene expression is crucial for cells to accurately produce functional proteins at the proper time and in the correct location. As a consequence, eukaryotic cells have evolved a finely tuned “gene-expression factory” that encompasses the routing of nascent transcripts through multimeric mRNA–protein complexes that mediate splicing, polyadenylation, nuclear export, translation and ultimate degradation. Recently, mRNA post-transcriptional modifications have been identified as a new layer of complexity in the regulation of eukaryotic mRNA life cycle, leading to the new field of epitranscriptomics. In particular, the N6-methyladenine (m6A) mRNA modification, which was detected 40 years ago in mRNAs but has long been overlooked, is one of the most common and abundant modifications on eukaryotic RNA molecules. Growing evidences support that this modification governs the recruitment of proteins to mRNAs to affect various mRNA related processes such as pre-mRNA processing (including splicing), mRNA export, storage, translation and degradation, by various mechanisms, which remain largely to be elucidated.
Over the past years, many factors involved in m6A modification have been identified and m6A marks have been found in many mRNAs where they mainly map to mRNA regions surrounding stop codons. The m6A modification is added, removed or recognized on mRNAs by factors dubbed writers, erasers and readers, respectively. Most of these factors are part of multi-protein complexes and are highly conserved in eukaryotes from yeast to human. Many of these factors are very important for normal cell development and/or have been linked to various human diseases including cancers.
Here, we propose to study the multi-protein complexes responsible for the formation and detection of m6A in mRNAs with the aim of clarifying the mechanisms involved in m6A formation/localization and the role of this modification in mRNA stability. We propose a highly synergistic workflow, based on complementary experimental expertises (yeast genetics, biochemistry, biophysics, structural biology) to pursue the following specific goals:
Perform structure-function studies of m6A mRNA methyltransferase writer;
Define the mechanism of selective m6A deposition in the vicinity of stop codons;
Decipher the impact of m6A on mRNA degradation and in particular on the recruitment of mRNA decay machineries.