Přehled o publikaci

Messenger RNA (mRNA) maturation is a highly intricate process involving multiple layers of regulation, which are closely tied to various quality control mechanisms. Among these regulatory elements, mRNA modifications have emerged as key modulators of gene expression, with N6-methyladenosine (m6A) being the most abundant modification in eukaryotic mRNA. The enzyme ALKBH5, an m6A demethylase, is conserved across species and plays a role in regulating m6A levels. At the cellular level, the removal of m6A by ALKBH5 has been linked to mRNA processing, export, localization, stability, and translation. Despite multiple studies on ALKBH5, we are still lacking good understanding of its molecular function. Our recent interactome analyses revealed that ALKBH5 interacts with the core exon junction complex (EJC) components, peripheral proteins, several mRNA export factors and 3’ end mRNA processing factors. This is in agreement with previous study showing that ALKBH5 depletion leads to poly(A) RNA accumulation in the cytoplasm. To further tackle the mechanism of ALKBH5 in these events, we performed high-throughput CRISPR/Cas9 genetic interaction screening, where we observed pronounced synthetic lethality for EJC components and several splicing factors. Furthermore, ALKBH5 depletion led to dramatic changes in mRNA expression and processing. Also, ALKBH5 KO cells displayed alternative splicing (AS) and 3’ UTR phenotypes. Compared to our previous studies on the second m6A demethylase FTO, ALKBH5 appears to promote AS, causing the inclusion of exons, by possibly catalysing m6A demethylation at the 5’ termini of mRNAs. Overall, our results reveal the importance of ALKBH5 in pre-mRNA processing and export.