The Core Facility EpiRNA-Seq in collaboration with researchers from the IMoPA lab and collaborators has developed a new method to map and quantify pseudouridines in RNA ! Focus on this new technique !

Developing methods for accurate detection of RNA modifications remains a major challenge in epitranscriptomics. Next-generation sequencing-based mapping approaches have recently emerged but, often, they are not quantitative and lack specificity. Pseudouridine (ψ), produced by uridine isomerization, is one of the most abundant RNA modification. ψ mapping classically involves derivatization with soluble carbodiimide (CMCT), which is prone to variation making this approach only semi-quantitative. Here, we developed 'HydraPsiSeq', a novel quantitative ψ mapping technique relying on specific protection from hydrazine/aniline cleavage. HydraPsiSeq is quantitative because the obtained signal directly reflects pseudouridine level. HydraPsiSeq requires minute amounts of RNA (as low as 10-50 ng), making it compatible with high-throughput profiling of diverse biological and clinical samples.

In collaboration with 2 teams of the IMoPA lab (UMR7365 IMoPA, CNRS-Université de Lorraine), the one from Pr Yuri Motorin and Dr Astrid Pinzano, and with 2 international teams (Pr Mark Helm, Germany and Pr D. LJ Lafontaine, Belgium), a human rRNA profiling has been performed, revealing strong variations in pseudouridylation levels at ∼20-25 positions out of total 104 sites. In addition, the dynamics of rRNA pseudouridylation throughout chondrogenic differentiation of human bone marrow stem cells has been also observed.

In conclusion, HydraPsiSeq is a robust approach for the systematic mapping and accurate quantification of pseudouridines in RNAs with applications in disease, aging, development, differentiation and/or stress respons.